How to be foxy/bitchy while having sex 🔥🔥🔥

Hey guys, lately my boyfriend has been telling me that he would like me to be more bitchy when it comes to sex. We used to fantasied about having a threesome but we stopped doing that because we got to a point when I got kind of uncomfortable because the other person we thought about was one of the girls he had sex with before he dated me (she’s his friend, and they see each other occasionally when his school friends get together)

And for me, there is this guy at my gym I really fancy and my bf knows so we thought about him too until I felt uncomfortable.

So, can someone give me tips on how to be foxy or playful when it comes to sex without involving the thought of that girl?