What do you think about me telling my female flatmates to stop talking about hot guys?
Why do you think it is okay to tell them? Are you just overly jealous and not liking other guys to be mentioned in front of you?
Maybe, I'm flattered when others compliment you and it's appropriate to do the same with others.
If that is something they like you shouldn't get in the way. Its part of their lives and they like having talks like that. You can't control your roommates.
How boring. I just want to get in the way of their good time.
You shouldn't try to control the actions of people that you live with. They may see you as overbearing and decide that they cannot live with you.