Knock before you come in

Yesterday my whole family went out ,and I stayed home . My boyfriend came over, and we ordered pizza. While watching the movie we got in the mood , and we were going at it . I locked the house door but didn't lock my bedroom door. I had forgotten my brother had a house key . While I was riding my boyfriend , my brother comes in and sees my boyfriend and I having sex . I got off my boyfriend and my brother just left the house . My mood of having sex went from a 100 to a 0 ...