@Gilly...
I was that way during high school. I would make jokes that killed my dignity just so I could see other people laugh. (see: SLE hidden agenda)
Ever since the military though, I've stopped doing it, they mostly beat it out of me. I still do it on occasion but not nearly the degree I used to. I think its simply a form of "I want to feel loved and appreciated right now, so I"m gonna go make some people laugh." Making people laugh makes me feel good. But I've sorta seen the behavior from the outside in some ILE's I've met and I had a guy in the military sit me down and tell me "you need to give yourself some respect." I don't think I took his advice but the behavior was sorta drilled outta me though psychological conditioning and people giving me disgusted looks.