Q: What do you call a pig that is no fun to be around?
A: A boar!
Explanation: A boring pig, that is. There are several names for swine in English including pig, hog and boar. And then when we eat pig it can be called bacon, ham, pork chop, … Who knew the pig produced so much vocabulary?!?!
If you are a bore, you are no fun to be around, not interesting. This joke plays on the word bore/boar which sound the same. The word bore can also mean to make a hole. I hope I am not boring you (being not interesting)!