To tongue the onion is to lick ones sphincter.
Guy 1: How was your date last night?
Guy 2: Dude, was awesome. I got her to tongue the onion!
by offious July 14, 2010
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To lick someone's anus and insert the tongue into the rectum during oral sex
1. There's nothing like tonguing the onion while you're going down.
2. Adam have you been tonguing the onion. Your breath smells like shit and I think she backfired.
by EvLovesGoldenRivets November 18, 2018
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