When I was 16 I lived in the basement and my girlfriend and I were on my bed under the covers and she was giving me a handjob and my dad walked down, somehow neither one of us heard him. he asked if we were going to eat dinner, he just turned around and walked up stairs when I said no. she stopped while he was there but finished me off afterwards and later that night after she left I got the "I don't ever want to see anything like that again, and you're not to be allowed in your room with a girl again" Luckily he doesn't stick to his word....
Unfortunately this leads into my next situation (same girl) we were all alone and seeing as how no one ever bothers me when i'm in my room (literally never, most times they don't know if I'm home) I was going down on her and my brother walked in, luckily she hid and I went and talked to my brother away from where she was in my room and he never knew.
not with that girl anymore but I've been close a lot of times with this girlfriend. luckily we can get away with her going down on me with my parents home. Unfortunately I don't live in my parents house or anywhere near it so now it'll be another month before I get to be with her again.