Me and a friend were bored so we decided to play murder mystery (after going from bedwars to guess the build, to party games, to disasters, and even uhc). Imo mm is an overall pretty boring game mode if you don't know what's going on, and neither of us knew much about it.
So we started trolling by giving fake comms, such as "playername is the murderer" (they were not the murderer). The lobby didn't really like this, so they accused my friend of being the murderer. That suited me just fine, I even joined with the lobby. Then he got shot and killed by the detective (who also died, since he wasn't the murderer). In the end the murderer won.
We played more games, and I got detective once. By this point, the lobby had gotten used to our shenanigans. Lots of games we'd just accuse each other of being the murderer (or other... non-desirable labels). This wasn't any different in the pre-game lobby.
When we spawned in, the first thing I did as the detective was shoot my friend.
It turned out that he was the murderer.