Verb: To make oatmeal in a bowl using urine instead of water, and then proceed to use your thumb to pack the "urine-oatmeal" into someone's anus.
1:

"I swear, if you fart in my cereal again I'm going to oatbowl you."

2:

Person 1: "Why do you have to use the oatmeal when you oatbowl someone?"

Person 2: "Well, otherwise you're just thumbing some dude's anus.
by Sphen5117 August 7, 2011
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