Top definition
A thunderously loud (hence the name) stream of piss that is unleashed in either of the following two situations:

1) When you first wake up in the morning and have to piss so badly that you feel like your bladder is about to explode;

2) After you have consumed an abundance of alcohol in a relatively short period of time.
1) John woke up this morning, immediately staggered into the bathroom and proceeded to cut loose a devastating stream of thunderpiss.

2) After Frank polished off the coffee pot full of whiskey and coke in less than an hour, he sprayed the sidewalk with thunderpiss.
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2
When your piss is so strong people waiting outside the door to use the bathroom can feel the floor vibrating from your piss hitting the toilet water.
"Thunder. Thunder! THUNDER PISS!"

"Man, Joe must have had a thunder piss. I felt it in the living room"

Thunder
Piss
by Pleasures Your Mom October 05, 2009
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3
Taking a piss on an electrical appliance.
Steve: "Mary Ann, I'm going to take a thunderpiss on our electric fence."

Mary Ann: "Have fun, swee -- wait, what?"

Steve: *background* "OH MY GOD!!!!!"
by Exoras July 07, 2006
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