peeing yourself as a kid.
tripping over something in class esp in front of a crush,
or dropping your pencil case/folder = giant mess
trying to hold in a cough during assembly and basically choking half way through.
letting out a seemingly silent fart, but it actually ends up being loud af.
cumming too quick.
^^ of these, embarrassing school things are great, and you can always slow down time in the moment the action is happening and really describe how it feels, the literal burning feeling inside, use metaphors etc.