Nerdy Science Blog has a whole post dedicated to hilarious science related Valentines.
And from physlink.com, some funny jokes:
“At the physics exam: ‘Describe the universe in 200 words and give three examples.”
“A student recognizes Einstein in a train and asks: Excuse me, professor, but does New York stop by this train?”
And I always laugh at Addams Family Values when Wednesday and Pugsley are standing on the roof, asking the all important question, “Which will hit the ground first, the baby or the bowling ball?”