What is Deffy?
1.
Slang for "definition".
Yo teach, what's the deffy of "missile tits"?
See
2.
Shortened version of definitely. Often used by teens.
A: "Look at that"
B: "That's cool"
C: "Deffy"
See
3.
To make an emberassment of oneself. To fail at suicide in an attempt of gaining attention.
Deffy slit his wrists like a little school girl.