piss like a racehorse

Etymology
An emphatic form of the earlier expression piss like a horse, due to the great volume of urine produced by horses every four hours or so.

Verb

 * 1)  To urinate profusely, especially in reference to a profound need to do so.
 * Pull over as soon as you can. I need to piss like a racehorse!

Hypernyms

 * See Thesaurus:urinate