my problem is that whenever i hang out with my girl, we often hang out with some of her old friends who she has known since high school

and they always talk about old stuff: events that happened in high school, people or teachers, funny events, or inside jokes that they know from their high school clique

and i totally dont have anything to add, because I dont know these inside jokes.
so I am usually just left being the quiet one. I end up lauging along with them but not saying anything except for the occasional "are you serious?" or whatever. just sort of nodding my head while they blather on.

so my question is, what should i do? i'm afraid that this girl might start to think ii'm a dork/too-quiet, but actually I just dont hav anything to add to their very one sided discussions.

-should i somehow try to jump into these "insider" conversations anyway?
-should i try to forcefully steer the conversation elsewhere? this could be akward
-should i just randomly throw in my own thoughts, like "yeah once when i was in high school XYZ happened..."
-or should i just let them have their nostalgic conversations because they seem to enjoy it a lot

I suggest having a conversation with her and letting her know that you often feel out of place before like you said she starts thinking that you are a dork and her freinds start thinking that you are boring. She should completly understand, and give her examples of"its not that I mind but how would you feel if we hung out with my guy friends and we only talked about cars (which hopefully she has no idea about ). And if were you I would encourage you to spend more time alone with her, or just let her hang out with the girls and you hang out with the guys OR you bring a friend along when the you are hanging out with the girls....who knows? you might end u playing cupid