A cytokine produced by T helper cells that causes severe masturbative syndrome. Commonly written as IL-25, this chemical messenger causes large erections and explosive ejaculation. Most common in caucasian males between the ages of 13 and 25.
"F*ck off mum! I can't help it! I have an intense buildup of interleukin 25! CLOSE THE TOILET DOOR!"
by Dr Drake June 29, 2006