Totally and utterly cool
I am ume riding on this girl
Unintentional Masturbational Explosion.
A not uncommon phenomina, where during masturbation, the ejaculation occurs in an unintended fashion, and the 'man juice' spurts out in an explosion-like manner, splattering everywhere, including undesirable places i.e. desk, keyboard, face
I was having a wank last night when I had a UME, it went all over the computer!