Simulpiss (v.) - pronounced sigh-mul-piss, like simulcast; the act of two or more people urinating in a toilet at the same time, often due to social situations involving overpopulation and consumption of adult beverages coupled with inadequate facilities. This act is most often performed by two men or a man and a woman.
-"Damn is this the line for the bathroom? I can barely hold it any longer!"
-"Its cool girl, just slide back a little farther on the toilet and we'll simulpiss."