It's means exactly what the word implies; you bite your tongue.
Usually this happens when you're talking to fast or while you're eating too quickly or something. It's hurts like a motherfucker, and the pain literally goes through your head. It's way worse when you bleed and then it swells it up, and whenever you brush the tip of your tongue against you're teeth, you could actually feel the cut.
girl 1--Shit, I just got a tongue bite from chewing my gum.
girl 2--Oh man, that sucks. I hate when that happens to me.
The actual act of a person having their face very close to another person's face (cheek to cheek).
One person will press their tongue (moving) inside their cheek causing a bulge that will be touching the other person's cheek, making them feel very awkward, weird, and slighty creeped out
When two people are making out, their tongues engage in something called "TongueWar". "Tongue Wars" involve two tongues fighting desperately for dominance while the usual motions of making out are temporarily stopped.
*Raquel and Farhad are making out*
*their tongues meet, and briefly tussle with each other*
*This brief tussle escalates into an epic Tongue War*
*Regular motions stop, and their lips remain locked as their tongues wage war on each other*
*Eventually a truce is formed and life goes on*