So basically, I've noticed that when ever I'm at a house party there is often a guy that tries to tell me what to do in front of women.

It'll be as simple as "Hey Jake, tell her what XYZ means" or asks me a favor. Am I being pretentious or would I seem like I'm killing the fun if I refuse? also it seems to turn women on as a lady I liked hooked up with this guy instead of me.

I'm new to social interactions and don't know how to deal with this (I'm a late bloomer. Doing a lot better but still don't understand social dynamics all the way)