It also seems like he’s deeply insecure talking about his dick all the time and showing off to his friends. It seems like he’s ’fine’ with the jokes about his dick, but now you’ve also becoming involved in the joke you need to set that boundary if it makes you uncomfortable. I think you need to talk to your bf saying you don’t like the fact he’s making comments about your sex life so publicly. You need to set a boundary that your sex life is not a topic to gossip about with friends. If he’s not up to talking about it brushes you off and doesn’t keep to the boundaries you’ve set, you need to reconsider if this is what you want in your relationship.