When you laugh so hard and for so long that your lungs literally feel fucked. To have a such a hard choking laugh that almost has the capacity to kill.
That dude is so funny, I can promise you pretty much every time you hang with him, he'll give you a good lung fucking... literally. Like he is that funny. He doesn't even need to say anything, you might die from laughter.
lung fucking is when your are having sex with a guy with a really big dick and it takes your breathe away.
(his dick is so big that measuring it up against your body, it would come up to where your lungs are.)
girl 1: "how was last night? ;D"
girl 2: "omg it was great! he was sooooo huge, i was having trouble breathing!"
girl 1: "haha you got lungfucked ;D!"
i love lung fucking!