An ignorant way of spelling "laughing". Used by someone who desperately seeks to be hip, cool and modern but in actuality simply flunked fourth grade spelling class.
A word used when "laughing" so uncontrollably you can not even spell correctly and simply don't give a fuck about your spelling errors.
Ted: "did you see Sarah dance like a stripper and fall off the table at the party last night?"
Collin:" Yeah bruh that was so funny I was laffin dude!"