The most annoying trope I know is the usual "I was raped by him but I fell in love with him" I actually like rape but this trope right here is overused and annoying.
The seme sticking his dick in the uke, with little to preparation. Also, the uke is somehow as wet as an omega, and said uke says something like "ahnnn I never felt this before" or "AHHHN i-it's so big!" reply
