The Brief: In the game Among Us, the phrases "is sus," "kinda sus," and "pretty sus" are used to casually accuse other players of being the impostor.

DEEP DIVE
Short for “suspicious,” “sus” is frequently used in Among Us as a way to imply that someone might be the impostor. Rather than basing accusations off of actual evidence, calling someone “sus” is an easy way for impostors to divert suspicion to another crewmate, including someone who knows that they’re the impostor. Although this method can backfire by arousing suspicion around the player who claims someone else is “pretty sus,” this tactic is known to be effective, and annoying to crewmates who are trying to expose the real impostor.
The use of this phrase is a popular topic in Among Us memes which note how easily discourse can be manipulated by a clever impostor and how a mob mentality functions within the game.
Among Us proves how unreliable eye witness testimony really is.
pretty sus
— Joseph Anderson (@jph_anderson) September 20, 2020
Never not sus from dankmemes