When a guy promises a girl great things in bed but all he does is give her 4 quick pumps then he tells her it was the best she ever had and leaves Cheeto fingerprints on her sheets.
To be interrupted in the moment of intercourse. This interruption ruins the moment. Similar to the cock block, but during sex.
Guy 1 - "Dude, not only did her friend unsuccessfully try to cock block me all night, when I finally put it in her I got a phone call from my mom."
Guy 2 - "Man, your mom hump trumped you!"