Whats a good excuse to stay the night at my Bf's when my parents KNOW im not staying the night at a friends?

My boyfriend is 17 and all my friends are 15 and such. So i feel my friends are immature and boring and i LOVE hanging out with my boyfriend. My parents know i lie about staying the night at my friends, and i REALLY want to stay the night at my boyfriends. We go to the club and partys and stuff and i like going, and dont want to just stop because i am to 'young' when i want to have a funn while i AM still young. So wheres a good excuse to go at night besides my friends???