1. A side-effect arising from a female foreign exchange student, alienated by language barriers, deciding to spend the semester in her bedroom, auto-stimulating.

2. A prog-rock band from Wisconsin.
"My God, dude! We slept together once before she left, but now she's returned there is a serious Köln Gusher Effect going on!"
"Hot! Did you have a towel?"
by Plummy Mummy July 12, 2010
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