Feeling like you're about to pee during sex?

So I've not been having sex that long, and I've never orgasmed from sex. But sometimes my bf is on top and it feels 👌🏼👌🏼👌🏼 and as he gets faster I get this feeling kind of like need to pee? What's that all about? Normally he'll finish before I get to find out what'll happen if we keep going. Any advice would be appreciated ladies xxx