1 definition by iamnotnjs

A large, yellow watermelon with the texture of a cactus and a stem shaped like a unicorn. Found primarily in Narnia and come to life on the third Saturday in June at exactly 1:43 A.M., EST.
"Oy! You there! There's a Tumbeast on my wanker!"

Well, get it off, Charlie, it's probably attracted to your Stunkmigeon!
by iamnotnjs February 22, 2011
Get the Tumbeast mug.