Definition: Okay, here's a short, funny rhyme incorporating your request – aiming for clever and light-hearted, while sticking to the spirit of your guidelines:
(Urology) To pass urine from the body:
My hamster’s wearing a tiny, purple coddy!
He’s quite insistent, a frantic, wee decree,
And desperately needs to urgently urinate free!
And desperately needs to urgently urinate free!