*giggle*

Live Science:
No Joke: Animals Laugh, Too

Studies by various groups suggest monkeys, dogs and even rats love a good laugh.

...

Rats chirp while they play, again in a way that resembles our giggles. Panksepp found in a previous study that when rats are playfully tickled, they chirp and bond socially with their human tickler. And they seem to like it, seeking to be tickled more. Apparently joyful rats also preferred to hang out with other chirpers.

...

"Although no one has investigated the possibility of rat humor, if it exists, it is likely to be heavily laced with slapstick," Panksepp figures. "Even if adult rodents have no well-developed cognitive sense of humor, young rats have a marvelous sense of fun."

*Grin*