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1.
Marking your territory by making it obvious on their facebook wall that you hooked up with him or her
Jan: So who is this girl that you sucked face with last night?

Dick: What are you talking about?

Jan: Don't eff with me, she Facebook Hickey'd you and let the entire world know.

Dick: Damn....

Eric: Joe, you better check your profile on facebook and erase what Kelly said about you before the rest of your girls read it.

Joe: What are you talking about?

Eric: Kelly thank'd you for a great time last night.

Joe: Awe shit, that could ruin my dating career. I hate the facebook hickey.
by ktespo July 03, 2009
 
2.
When a girlfriend or boyfriend (usually girlfriend) constantly tags their partner in facebook posts, and writes "I love you!" and "Can't wait to see you tonight!", etc. on their wall. It is done as a show of territory, usually in a new or troubled relationship.
"Wow, check out the amount of facebook hickeys on Adam's wall from Katie."

"Ha! Too bad his relationship status is still single!"
by nunya0129 July 12, 2012