FIS
Means to Fart In Self. When you're in a situation, like with a new boytoy (or fish) and you have to fart so bad that it goes up into your stomach making a loud rumbling, grumbling, farting sound. To which you say "hmmm I must be hungry" in a sad attempt to cover up.
Claire - Oh man, I was at Rusty's this morning, and my gas was so bad that I was Fissing like crazy!
Ann - Dude you should have just broken the ice and dutch ovened him
Ann - Dude you should have just broken the ice and dutch ovened him
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