Yiffing is a combination of words "sniff" and "yell" made up by MatPat's wife Steph in their livesteam for a game Dayshift at Freddy's, as she didn't know what it actually meant.
MatPat: "So, yiffing is, for those who don't know-"
Steph: "Wait, I should guess! I think that a yiff is probably a yell and a sniff at the same time."
Usually refers to cyber sex between two or more members of the furry fandom. Originally refers to the sound that foxes make when mating. Members of the furry fandom may use the term to refer to actual sexual contact, usually in a lighthearted manner.
It is also a term used at furcons to inquire about sexual intentions between fursuiters.
The anthro fox smiled at the mass of horny furres, knowing that a good yiffing session would soon follow.
while dressed up in animal costumes, participants grope, fondle, and hump on each other for sexual gratification. no actual sex involved. Usually done in a group setting.
Peter "rabbit" and Jane "cat" fondled each other through their costumes while yiffing at a furryfriends party.
When you have to pee in a movie but don’t want to miss anything, and must do the following mental equation: will the amount I have to pee cause enough discomfort to diminish my attention capacity for the remainder of the movie to an extent which is greater than the amount of the movie I would miss by making a mad dash to the restroom.
I saw Satantango last night, wonderful film but by the 5th hour I had to start doing pee calculus.