(Verb) The act of rudely logging off of facebook while in a chat with someone else.
You: "Sup dude, this is a cool conversation we're having"
Friend: "Yeah totally im just casually chatting about random stuff like harry potter"
*FRIEND IS NOT AVAILABLE TO FACEBOOK CHAT. MESSAGES WILL BE RECEIVED WHEN THEY NEXT LOG IN*
You: "WHY DO YOU KEEP YANGING?!?!?"