When you (accidentally or otherwise) catch your own semen in your mouth after busting a load.
Jimmy was masturbating vigorously the other day and gave himself a Japanese Fountain. Dude now has a new fetish.
by Dinrael May 16, 2015
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When you eat nothing but chili for a couple of days while holding off the urge to take a shit and when it finally becomes unbearable you stand over your other (preferably in a bathtub) and spray your fountain of explosive diarrhea all over them.
My relationship with my old lady went to the next level when she let me give her a Japanese War Fountain
by Spnanksbdv February 28, 2020
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