Accidental Pervert: While explaining why he has pinkish sheets on his bed, one of the reasons he gives is "so that [girls] don't suspect that I'm a sexual predator," which is immediately followed up with "WAIT NO- WAIT, I- ...umm, ignore that. Ignore that."
Actually Pretty Funny: In many of his collaborations with others (especially with TotalBiscuit), he will get on his partner's nerves with his antics... only for them to end up laughing too hard to tell him to shut up.
Brought up to eleven in his Skyrim Let's Play, where Jesse insists on following every fox he sees for no particular reason even though he acknowledges that they almost always lead him into trouble, especially the white ones.
Lest we forget the infamous blow up during a Gamestation Podcast during discussion of the morality of day-one DLC: "HOW THE FUCK DO YOU KNOW THAT, YOU COCKGOBLIN!!"
There's been more than a few times in which Jessie and TB have gotten into more than a heated debate about difficulty in games. Though it seems to have died down lately because TB has came out against Nintendo Hard difficulty, it hit its peak when TB announced that he was done playing World of Warcraft due to nerfing of dungeons, which Jessie made a counter video to (which never mentioned TB by name though many could suspect that since TB was the elephant in the room during the debate, Jessie was mainly targeting him with the video).
Cluster F-Bomb: During his nineteenth episode of his Shadow Warrior Let's Play (aptly named "RAAAAAAAAAAAAGE!!!"), he became infuriated when the controls wouldn't work correctly. What followed was an unapologetic flood of cursing and insulting the game.
"Lizzie" (Derkeethus) is described in this way in the Skyrim playthrough, often keeping a straight face in the middle of Jesse's silly antics and mentally retorting to Jesse's bad jokes. But he doesn't actually talk outside of "personality".
Kiskae would like to think of himself as one, making subtle remarks in the chat for anyone with a keen eye during the "RPG Makers" videos and invoking the trope directly with a Shout-Out to this very page. But like Lizzie, he doesn't actually talk, and it's difficult to communicate sarcasm through telepathy and texts.
On the Co-Optional Podcast, when his followers on Twitter were unfollowing him and following Dodger instead. As one person said: Jesse broke.
Determinator: Jesse's mission statement for his channel is that whenever he starts a new series, he will see it through to completion, no matter how bad it gets (with the exception of Lightning Returns, see below.) One example is when he hit a Game-Breaking Bug during the final battle of Metal Gear Rising: Revengeance, which nearly caused him to stop the entire Let's Play right there. Eventually, however...
I give up on giving up. I am a gamer. I CANNOT walk away from this stupid ass boss. BUG OR NO BUG. I will win.
He then works out a way to do it by changing resolutions multiple times during the final boss fight.
The Ditz: Jesse. It's bad when even "leading" the RPG Makers, people doubt his intelligence.
Omzit: When Jesse knows more than you, there's something wrong.  Jesse: Seriously.
Eagleland: Frequently invoked and parodied by Jesse. Especially on the RPG Makers.
Epic Fail: In a few games, but mostly throughout the Terraria series.
For example, every time either TotalBiscuit or Jesse try to kill each other with bombs. They manage to spectacularly fail and only kill themselves each and every time. It would help if they realized that you can't kill people in your own team with explosives, only yourself.
Fun with Acronyms: The "OMFG" in OMFGCata is explained as meaning "One Moderately Funny Gamer".
Backronym It originally stood for Ohh My Freaking God, Cataclysm!, it was changed after the Cataclysm Beta was concluded.
Genre Savvy: He has been commented by fans and friends alike that he has a knack of figuring out the plot twists of games far before the game itself reveals them. Examples include:
Almost as soon as he meets the resistance in Dishonored he predicts they will betray him. Guess what happens in Part 38.
In his Bioshock Infinite playthrough he is able to figure out the alternate universe themes of the game just by a few early moments of foreshadowing.
Displays a fair amount of savvy throughout his play through of Outlast. In particular in Part 12, he declares, with fair reason, that the next door will reveal the big twist. The door opens into an area unlike any other in the game so far.
Hidden Depths: Jesse was a Theater and History major in college, and in fact used to teach history to troubled teenagers. If you were in doubt of his History Major, look here.
Dodger, quoting Jesse regarding the map in her room: "If there's a country I can't find on a map, it's probably because they've changed their name since I learned about it."
He has a plaque given to him by his former school district as being rated the best history teacher in it.
All of the Dishonored videos are titled with a "Dis-" prefix. It culminates in the finale - "DIS is the End". Averted, however, in the DLC, which has no such system. To be fair, by this point, Jesse has exhausted every possibility of "Dis-" prefixes.
He keeps calling Ghostz_eu 'Comrade Creeper' when his avatar is essentially a communist slime. Ghostz used to correct him before but now has given up. He still refers to Lewis' avatar, the same but in a lab coat, as "Dr. Slime", and upon the Fridge Logic being pointed out to him in an episode, it's become evident that he's continuing to do it to promptangry buttclenchesfrom many of the viewers.
Man of a Thousand Voices: Jesse is actually a professional voice actor (having around 4 notable voice personas with the rest being a mashup from them or movie references).
Misplaced Nationalism: Invoked and parodied by the crew (especially the RPG Makers), because of how there's just as many Europeans as Americans working together. Even though they're all good friends having fun, there's very likely to be some mention of another country followed by pointing and laughing. Especially Denmark and America.
Missing Episode: The three lost Terraria videos. All of them had the videos lost (the second and third by accidental deletion on TB's part) but the audio saved, and TB has released the second and third lost episodes (meant to be before episode 32) as an audio podcast. The first one, meant to be before episode 13, has not been released, according to TB the audio is so corrupted it's irreparable.
Numerous are played with. Especially prominent in the RPG Makers series, where half the on-screen cast is from America and an increasing majority are from mainland Europe: they will jibe on stereotypes, such as Omzit demanding that Jesse "give him his money" because of America's debt.
Jesse in return has an exaggerated "Durka durka"-type voice impression of Sweden, Holland, Finland, and even Germany.
Also includes self-lampooning, such as Mike's legendary ironic phrase "Trust us, we're Americans."
Non-Indicative Name: While OMFGCata obviously stood for "OMFG + Cataclysm", the channel has since expanded into general gaming content, with World of Warcraft content eventually fading out. As Jesse has posted on his FAQ on top of the channel box, OMFGCata stands solely for World of Warcraft in the same way that TotalHalibut is about fishing. It has now been extended to, as of the second Game Station Podcast, "One Moderately Funny Gamer Constantly Annoying Those Around."
Jesse is, unbelievably enough, a 30 year old man who still keeps in step with teenagers today on internet fads. Lampshaded by TotalBiscuit, who is 27 and still more mature than Jesse, in their TerrariaLet's Play.
Further Lampshaded in the 6th Podcast, when Jesse comments that TB sounds like an old man reminiscing on the old days of online play, TB snarks that among he, Jesse and Let's Play/Simon together, he's the youngest male there.
Jesse has started transcending into Man Child territory with the 8th podcast, when he showcased a video by Lucahjan that contained nothing but testicle jokes, and TB starts questioning his maturity.
Patriotic Fervour: Briefly becomes a patriotic, bomb-throwing Texan in his Terraria series.
Rage Quit: There is only one game that he considers to have ever truly quit, and that is Lightning Returns: Final Fantasy XIII. And by the time the game footage cuts out to Jesse's explanation (In which he spoils the game so don't go looking for it if you want to learn for yourself) as to why it is over he's completely furious. The last episode of the three part series is appropriately named "THEN WHAT'S THE F*$#ING POINT?!"
Jesse constantly falling to his death in Terraria. Especially after TB got a Lucky Horseshoe that he had earlier promised to give to Jesse to prevent such occurances.
When he was doing videos of the Worgen starting zone in the Cataclysm beta, any mention or meeting with Darius Crowley is accompanied by a clip of "MISTER CROOOOOOOOWWLEY" *bum bum bum* Later on, in any number of different videos on a variety of games, Jesse would break out a verbal "MISTER CROOOOOOOOWWLEY! BUM BUM BUM!" whenever the name "Crowley" makes an appearance.
"Oh, Garlic! I can use that for crafting!"
His playthrough of Dead Space had him jumping in fright whenever the other two crew members contacted him, eventually driving him to scream "STOP DOING THAT!" at one of them when it happened for the umpteenth time.
Rule34 — Creator Reactions: Jesse knows there is Rule 34 about him and TB, and his response: Write more and add tentacles and Warcraft females. TB's response, meanwhile, is a Flat "What." and declaration of losing the will to live (more-so than usual with Jesse).
Seinfeldian Conversation: Basically the whole Terraria series with TB, and a significant portion of the Saints Row series with Crendor. Ironically, Jesse claims these are his pet peeve when watching gameplay videos, since he thinks the game should be the focus instead of just a background for whatever you feel like talking about.
Shown Their Work: Jesse knows quite a bit of American history while playing BioShock Infinite. He notes that the "Battle of Wounded Knee" was really a massacre of innocent families, and is able to name a great deal of presidents when he encounters the Patriot Heavy Hitters.
Worth noting he knows these things having been a history teacher in the past.
Sore Loser: Jesse does NOT take defeat well. He has stated many times that the primary reason he refuses to play competitive games is because it stresses him beyond tolerable levels and that losing, especially in front of an audience, makes him incredibly depressed.
SpaceX: Used in the description for his Dead Space series, and occasionally used for some of the enemies in the game. The first game features "space babies" and "space butt" prominently, and the sequel adds "space raptors".
Let's not forget the great Space Butterfly. May its wings flap eternally, as it dreams the world we live in.
In the "Eye of the Creeper" video, SlyFoxHound (from Machinima Realm) drops by to offer Jesse some advice on Minecraft. And also to blow up his shanty. Later, Sly pops in on an RPG Makers Minisode, only to get shot at by arrows as the crew test out their newly trapped puzzles.
The Yogscast did as well for one episode, also trying to give Jesse Minecraft advice.
Straight Man and Wise Guy: Jesse manages to be both sides of this with different people - he plays the wise guy to TotalBiscuit's straight man, but also plays the straight man to Crendor's wise guy. Lampshaded in the 17th podcast with all three people mentioned above as guests.
TB (Inquiring about Jesse and Crendor's Saint's Row LP): Who gets to play the incompetent one and who gets to be the douchebag? Jesse: Oh, oh! I'm you!I'm YOU! TB: Oh. Jesse: I dunno how it happened, I became you! TB: This is how the pyramid works...
Stupid Statement Dance Mix: His UFO Commander song, which was made by splicing a bunch of voice clips from his Game Dev Tycoon playthrough and setting it to very catchy music.
Summon Bigger Fish: Tries to invoke this in his and TotalBiscuit's Terraria playthrough, in which he attracts the attention of a Wyvern and tries to make it kill TB. It doesn't work.
After the first big jump scare in the introduction movie.
"OH SHIT!*Hysterical laughter* Ohhhh, fudge. *Laughs* Ohhh my god, are you kidding me? You guys suck, I hope you understand that."
Too Dumb to Live: In Amnesia: The Dark Descent part 22, Jesse tries to climb inside of and close the doors of an iron maiden. And then he tries to do it again so that he could read the text that appears upon clicking on the thing normally. Not 5 minutes later, he tries to jump inside of a brass bull. Lampshaded by the Co-Dependent girls on both occasions.
Took a Level in Badass: In Totalbiscuit's Terraria playthrough, for the first thirty-one episodes he is less advanced than TB, having a double jump in comparison to TB's grappling hook, no mana, and less awesome gear. Over the course of the two lost episodes in between 31 and 32, Jesse gains 40 mana points, an Orb of Light spell, and rocket boots and a lightsaber.
Also during Dodger's 12 hour live-stream where Jesse declared war against Dodger. Which led to Crendor, Myndflame, TotalBiscuit, and Husky being casualties of war. Completely Played for Laughs but some people took it too seriously.
The Uriah Gambit: Jesse attempts one of these in Part 34 of his Terraria Let's Play, luring a Wyvern into combat in an effort to kill TotalBiscuit. This being Jesse, however, it backfires, with the Wyvern murdering Jesse twice and wreaking havoc within the duo's base.
Verbal Tic: Has a few but the most prominent is "And that's a thing"; other members of Polaris like TotalBiscuit and Dodger seem to have picked it up from him.