Best part:

(…) Brecht’s team even taught the rodents to play hide and seek. At the beginning of the game, a rat was enclosed in a box while a researcher hid somewhere in the room. The researcher then opened the box using a remote control, allowing the animal to jump out and begin “seeking.” When the rat successfully found the hidden scientist, it was rewarded with—you guessed it—a tickle. The rats were also given the opportunity to hide while the researchers looked for them, and they proved to be especially good at coming up with creative hiding spots. Their ability to strategize was “almost spooky,” Brecht recalls.

(…) Brecht’s team first made sure the rats were comfortable with their new playground, aka a dimly lit plastic box, as well as their human playmates. The researchers then played games of “chase the hand” and tickled and the animals on their backs and bellies (see video (…) for an example from a previous experiment). In response to the tickling, the rats shimmied in delight and let out endless “giggles.”