How to stop crying or laughing at inappropriate times

I swear my humor isn’t fucked up or anything, I just zone out and end up thinking about something that makes me laugh. The problem is that happens a lot when a teacher is talking and it usually ends badly, especially if they say something like, “You think this is funny?” in a stern voice.

Also what the fuck can I do to prevent myself from crying when someone’s yelling at me? I’m at a point where I literally might just ask me friend to yell at me all day so I get used to it.