I seem to recall that I once read a story (like, a real-life recollection in a magazine or something) where a guy accidentally grabbed Vaseline instead of the KY next to his bed (the lights were off) and after he was going at it for a bit on his wife, she yelped and ran into the bathroom and washed out her butt (cause it was all ICKY with Vaseline) and was creating a burning sensation. Then again, I might have just dreampt I read that.