It's what happens when your lover/hookup sucks on your tongue so hard you feel it get numb in his/her mouth. It leaves purple bruise spots afterwards.
Jack is a horrible kisser. When we were making out, I stuck my tongue in his mouth. He sucked it so hard I couldn't get it back in mine before it went numb. It was painful and turned me off. A little gentle sucking is fine, but not THAT much! Don't sign me up for a tongue hickie in the future.