Amnesia Danger: His LP of Super Mario Galaxy was recorded years after Josh had last played the game, with the result that his memory of many levels and mechanics is vague and sometimes even feels like a blind LP. This trope naturally ensues on harder levels, along with hilarity.
And That's Terrible: From Ocarina of Time, "Also, he wants to rape me, and that's not very nice!"
Didn't Think This Through: Said word-for-word in his playthrough of the A Hat In Time prototype, where he rides a firework out to a faraway island in the level, jumps off it... and then realizes, without a firework, he'll have to swim alllll the way back.
Failed a Spot Check: In part 1 of the Four Swords Adventures LP with NintendoCapriSun, 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.
Girls Are Really Scared of Horror Movies: This trope is subverted in the common comedic way in Josh's livestream of Dead Space with his girlfriend Brooke; before they start, he talks up how easily scared she is, but when they actually play, it's Josh who sounds more terrified, as Brooke lampshades.
Gorn: He gets the "Bloody Mess" perk in Fallout 3 to invoke this.
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.
ProtonJon: 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.
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".
"Welcome to Part 34 of Let's Talk About Banjo-Kazooie While Playing Super Mario Galaxy"
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.
In episode 32 of his Let's Play of Super Mario Galaxy, he talked about how much he hates the phrase "I hope this helps!" Three guesses what all the comments were.
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.
In Banjo-Kazooie and its sequel, he sings "Make me a bear and bird again (bear and bird again!)" in a falsetto voice when reversing a transformation.
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.