Accidentally Accurate: At the start of Rayman Origins, Josh and Super Jeenius nickname the game "Rayman Oranges" after Josh slurs the pronunciation. Then the opening cutscene features Rayman...eating oranges, and orange slices are a recurring enemy in the game. They repeatedly point out how strangely appropriate the spur-of-the-moment joke becomes.
And That's Terrible: From Ocarina of Time, "Also, he wants to rape me, and that's not very nice!"
Armor-Piercing Question: In one of his Jepscon vlogs, he begins arguing with Chuggaaconroy and ProtonJon (well, mainly Jon) over vlogging and claims it to be an art. The others begin mocking this, then...
Josh: Let's put this in perspective here. Is let's playing an art?
Big "YES!": Tends to take this trope to insane levels for a short time upon completing one of thoselevels.
Blood Knight: States his intent early on in his Fallout 3 LP to play through the game as one of these.
Brick Joke: An offhand joke about coming back to play a particularly difficult level in Donkey Kong Country Returns when the world ends on 21st December 2012 actually results in a bonus video of Josh and Super Jeenius playing through That One Level, uploaded on that date.
Some of these reappear in Rayman Origins, along with others such as "Balls on chair--now I'm ready for some things", one of them referring to 'lumms' and the other correcting the pronunciation to 'looms', and mispronouncing the word 'Origins' in the title in different ways.
Failed a Spot Check: In part 1 of the Four Swords Adventures LP with Nintendo Capri Sun, Super Jeenius, and P Cull 44444, they step on a group of switches which spawns a couple of big green force gems and a couple of chests right between them. They immediately grab the force gems and move on to the next screen without opening the chests or even taking notice of them.
Hype Backlash: invoked Regarding Raphael the Raven's boss fight. After hearing numerous people rave about how awesome it was, the fact that it was so lengthy and frustrating did not endear it to him. He admitted it was cool, but he didn't find it fun.
Iconic Item: Josh has a random painting of a cow in his apartment, which is often referenced by people doing fanart or animations of him.
In Rayman Origins, on encountering several examples of a Helpful Mook in the form of a toucan-like bird that launches Rayman upward when he jumps on its beak, Josh dubs them "Attacking Toucans".
Large Ham: He occasionally throws his mic levels into the red.
Let's Get Dangerous: When he gets serious about finishing a hard level, he gets completely silent to focus. He describes this as taking a cue from Super Jeenius, who did this as well when they played Donkey Kong Country Returns together.
Proton Jon: I got three assholes with me and they're kinda dicks... Like, look at the face on that guy. Face only a mother could love. (About Josh) And then we got this asshole. Josh: Oh, thanks! Jon: No, actually, he's pretty cool. Then we got... well, we got Tim.
The Nicknamer: He gives nicknames to many of the enemy types and objects in Yoshi's Island. Also, "Bitchfish" from The Wind Waker.
Nostalgia Filter: Invoked in Glover, which Josh says is objectively not a good game, but one he still likes just because he happened to play it when he was a kid.
Running Gag: When reading out onscreen instructions, he replaces any reference to buttons with "something". So for example a caption reading "press A to rotate the item screen and B to close the inventory" will be read as "press something to rotate the item screen and something to close the inventory".
Schmuck Bait: In the last episode of Donkey Kong Country Returns, while they're doing difficult jumps between floating platforms, Super Jeenius tells Josh "There's a giant Blanabba (banana) in the background, don't look at it!" Of course he does and immediately misses the jump and dies.
Seinfeldian Conversation: Josh and Super Jeenius are prone to them in their co-ops, and also Josh and Tyler in their Versus projects to a lesser extent.
Sir Swears-a-Lot: Varies. At one point he started to cut back on or censor the swearing in his own LPs, though he still swore A LOT in his collaboration videos. Later, he returned to swearing in his own videos.
Straight Man and Wise Guy: Josh has this dynamic with Super Jeenius when they team up for co-ops. Usually Josh is the Straight Man and Jeenius is the Wise Guy, but sometimes they trade roles.
Stupid Statement Dance Mix: People seem fond of making these for "Oh my god! What the heck was the what the what the what?". Some example here and here
Suicidal Gotcha: Of an accidental variety, but in the Yoshi's Island level "Goonie Rides," he found himself plummeting into the abyss, shouting and weeping, sure he was done for... only to see Yoshi rise from the bottom of the screen, having landed on the back of a random Goonie flying by. From his perspective, it probably counts.
Tempting Fate: In episode 23 of "Donkey Kong Country Returns", Super Jeenius takes the top path of a level and Josh reassures him the bottom path won't have any of the things they need to collect, like a letter...only for a letter to immediately appear down there.
Worth It: Collaborating with Lucahjin on Barbie Horse Adventures. "This may have just ruined my Let's Playing reputation. But it was worth it for 'My Balls.'"