A word used inside of
furry fandom based on the word
yiff.
The word's primary uses are to declare
somefur or something as either
sexy or
horny, although it can also mean less sexual things such as
interesting, or
exciting.
Examples:
"Check out that black fox-morph! Murrr... He's one yiffy hunk of meat."
"Did you see that new pic on the VCL? Man, did that ever make me yiffy."