Here are some entertaining jokes regarding labs:
1) How many dogs does it take to change a lightbulb? Lab: Oh, me, me!!!! Pleeeeeeze let me change the light bulb! Can I? Can I? Huh? Huh? Huh? Can I?
2) What kind of dog does a Mad scientist have? A Labratory Retriever!
3) Have you heard about the new dog cross-breeds? They crossed a Labrador Retriever and a Curly Coated Retriever. The new breed is a Lab Coat Retriever, the choice of laboratory researchers.
4) They crossed a Bloodhound and a Labrador. The new breed is a Blabador, a dog that barks incessantly.