My little bird with throat so red, Sings sorrow, sorrow, sorrow...
Okay, this is actually a Physics joke (of such caliber that it is considered the worst joke in the department), but I think you'll get it:
All the Physicists were playing Hide-and-Seek. Einstein began counting, and all the others ran off and hid. Except for Newton, who pulled a piece of chalk out of his pocket and drew a square around him with sides 1m. When Einstein finished counting, he turned around and said "Aha! Newton, you are out!"
To this, Newton said "No, I'm not out. Pascal's out - I'm one Newton per square meter!"
He sings to the little dove that's dead, Sings sorrow, sorrow, sorrow...Visit my Stamp Emporium for all your stamp needs!