Contraction of "what is this I don't even". Typed when you're too astounded to tap out more than 9 keystrokes. Spoken when you're too stupefied for words.
NOT to be confused with whatever.
ME: ZOMG this dude tossing a tuxedo cat toward the hula hoops on the wall while two girls were kissing behind booze bottles is the best LOLcat EVER!
YOU: what even