The contraction of "what" and "not". Similar to: haven't from "have" and "not"; shouldn't from "should" and "not"; and wouldn't from "would" and "not".
Michael, Davey, Jhonny and Gherardo were sitting about kibitzing over the woeful shortcomings Obamacare. Suddenly, young Jhonny blurts out: "I can't believe Agnes has sex with her alligator, Mitur, Bud and whatn't!!!"
by Jhersey Jhonny November 15, 2013