What about science puns?
My teacher threw sodium chloride at me... That's a salt.
I told a history major a chem joke today... There was no reaction.
Not a pun but still a solid science joke:
Schrodinger and Heisenberg were driving on the freeway when a cop pulls them over.
"Do you have any idea how fast you were going?" asked the cop
"No, but I knew where I was." responded Heisenberg
"You were going 100." said the officer, confused.
"Damnit! Now I'm lost!" he responded
Suspecting drug use, the officer checked the trunk.
"What the fuck?! You guys have a dead cat back here!!"
Schrodinger responds "Well we do now, asshole!"