Knock-knock. Who's there? To. To who? No, to whom.
Knock Knock! Who's there? Testicules. Testicules who? Pillow for penis .
Q: 0 is false and 1 is true, right? A: 1.
Schrödinger's cat walks into a bar and doesn't.
Q: Why did the computer go to the dentist? A: Because it had Bluetooth.
Knock Knock! Who's there? Zany Zany who? Zany body home?
Fast way to screw up someone's Knock Knock joke...? "It's open."
Knock Knock. Who's there? Opportunity. Don't be silly - opportunity doesn't knock twice!
Q: Why can't lawyers do NMR? A: Bar magnets have poor homogeneity.
A photon is checking into a hotel and the bellhop asks him "Do you have any luggage?" The photon replies, "Nope, I'm traveling light."
Q: What is the chemical formula for "banana"? A: BaNa2