We've played all sorts. Mostly it's individual audience-members who come to mind as problems. The man with a condom on his head dancing on the table, teachers, the "...friend who sings and plays guitar and please let him." Silly questions and unlikely requests -- although I quite enjoyed them. I've got a whole list.
I did have a gig where I was asked to walk around a small room singing, unamplified, at the various tables while a band -- amplified -- played on a stage at one end. People thought I was great though and the band took a lot of breaks. I got to practice mime.
Weddings -- well they're there to look at the bride aren't they. Icing on the cake if they listen to the music too.
Cheers, Joy