Why are puns?

I'm reading a book about anti-gravity. It's impossible to put down. -
I wasn't originally going to get a brain transplant, but then I changed my mind.

Its a play on words. Brain/ changed my mind.

wire puns.

What else do you learn at Pun State University?

For very serious grammarians, they are punishment.

why indeed

Mainly because they are witty, clever, and fun, as well as thought provoking.

Because they're fun!!

wut