boo-boo face n. a pout or pouty facial expression; moue; boo-boo lip, an out-thrust lip. Editorial Note: Probably from the facial expression children make when they have a boo-boo ‘minor injury.’ (source: Double-Tongued Dictionary)
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actually…its more of a i smell boo-boo face. you know like you just smelt crap. i.e boo-boo.