* EarWorm: Many of their songs, but special note for the "[[https://www.youtube.com/watch?v=ZsQcyhBsSjI ShamWow Song]]".
* HilariousInHindsight: "Epic Rap Battle" was released in 2010. Almost a year and a half later, they appeared in ''WebVideo/EpicRapBattlesOfHistory'' as the Wright brothers.
** Almost a year and a half LATER, they returned as Leonardo (da Vinci) and Donatello (di Niccolò di Betto Bardi).
* MemeticMutation: "Nope! Chuck Testa!"
* MomentOfAwesome: The [[https://www.youtube.com/watch?v=-uwY3sjqYX0 Fast Food Folk Song]]. They sing their order into a Taco Bell drive-thru, and the cashier gets the ''whole thing'' right. Unrehearsed.
* NightmareFuel: '''CLOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOWN...SHAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAARK!!!!!!!'''
** And, for some people, "Christmas Face". (Especially Grace Helbig's face. You must see it to believe it.)
** Link's reaction after eating a ghost pepper. As one YouTube commentator put it, it was like he became possessed.
** [[SurpriseCreepy Observe how little by little]], [[https://www.youtube.com/watch?v=M2WTRqCu_DY Rhett and Link's vacay becomes cray-cray.]]