In a video game, to gather information on an area hidden in fog of war by charging in. To check for enemies with your face. Seems to have originated in League of Legends where vision-obscuring bushes allow champions to wait hidden from view in very close proximity to their opponents.
I told Annie not to facecheck the brush, but she did anyway. Garen scored first blood.
Facecheck, noun. The impact one's face into the feet or fists of another, usually under the misguided impression that this will somehow lead to victory. When used in gaming, a facecheck is any rush by an inferior party into a superior one and the subsequent inevitable outcome.
Can also be used as a verb, to facecheck is to make said impact.
Man, I can't believe Jim facechecked Roger like that. He's twice his size, what was he thinking?
When you're rude to a waitress, 'facecheck' is what she does to you in return. Rather than fold your check and gently place it on the table, she instead removes a pin from her hair and proceeds to embed the check to your forhead.
"Oh no you didn't, woman! Aint no $5.15-an-hour waitress-hag gonna facecheck me on my dime!