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When a guy eats a girl out while she is on her period.
Ewww d00d, you ate her out on her period just now? Your have a crimson chin faggot.
by Kvansn April 15, 2008
when 69ing with a girl on her period, eating out her pussy with one's tongue and massage her clit with one's chin.
"I crimson chin'd that pussy"
"hardcore crimson chin action"
by anonymouspawnymous January 12, 2012