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3.
a sudden, hysterical outburst of laughter; uncontrolled. usually followed by assorted jibberish. almost always expressed through text. usually a misspelling of lmfao.

read: lmmfao, lmfao, lmao, etc.
me: <insert joke>

.....

you: KNFAI
by vege May 03, 2004
 
1.
a shift of LMFAO
often referred to as a pokemon
A.D: KNFAI
L.M: POKE-BALL POWERS!

---another convo-------

A.D: KNFAI
J.R: What?
A.d: sorry *LMFAO
by magicalhippie April 16, 2007
 
2.
When something makes you laugh so much words cant describe it, you're left with "KNFAI", the jumbled jargon.

Mostly typed while on the computer, though it can be used in rl.
You hear or see something so ludicrous you can barely hold it in.. you would KNFAI..
by Gray Borgia April 23, 2004