Wetchup Share definition Flag That grotesque ruddy,oily & watery substance that squirts onto you're cheeseburger when you forget to shake the ketchup bottle. Fuck! I forgot to shake the ketchup bottle and now my burger is slathered with wetchup.... Fuck! Wetchup by Tropes May 23, 2006 0 0 Get merch Get the Wetchup mug. Buy Now — $32.95 See more merch