While a girl is giving you The Blumpkin (Taking a shit on the can while receiving a blow job), your stomach becomes sour and end up vomiting all over her hair. This can be caused by excess drinking (blumpkin salad w/ italian dressing), or food poisoning (blumpkin salad w/ bleu cheese).
Jake: Dude, I gave Krista a Blumpkin Salad last night with tons of dressing.
Matt: No way, what kind of dressing?
Jake: She had the bleu cheese, we went to a chinese buffet.