A sexual act where a man go's down on a female and notice's a nasty taste or smell, he than after tasting it kisses the inside of her thigh, then go's up n sucks on her lip so she has to deal with a nasty taste and odor for the next few hours not knowing what it is, when in actuality its the smell of her rotten onion on her lip.
Dude that chick was nasty so I gave her a fuckin "onion lip"!
by Jonutz March 10, 2011
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