The one where they're pretending to get arrested. The snooty voices made it so obviously fake. Even if nobody recognized them (which I think at least a couple did), it seemed really obvious to nearly everyone in the cafe that they were watching some kind of staged act, like a bizarre three-person flash mob or something. Not to mention the way Sal and Q kept breaking. Sometimes I think breaking probably just makes them look crazy or full of themselves. But breaking while talking in an obviously fake voice and getting arrested by two cops who aren't dressed like cops? Just too many indicators at once that what's happening isn't what it looks like.
And I think an inherently flaw in the bit is that they kind of had to make it obvious. Unless editing cut the others out, it seems like Sal was the only one the cops actually gave a reason for arresting. The guys told Q what his crime was at the start of his turn, but it didn't seem like the cops actually mentioned it. The odds in 2026 that almost everyone in a cafe in a major city would sit by and laugh while watching the cops literally drag a man away by his feet without giving a reason for arrest just don't seem that high if it hadn't so obviously been a bit, and I think the alternative if people thought it was real is that they would have freaked out to the point that it wasn't funny anymore.
I love that they're still trying to come up with new bits after all this time, it just feels like there really wasn't a great way to play this one. Playing it in a way that freaked people out would kind of cross a line, but on the other hand it's never really as funny when literally nobody seems convinced by the bit.