"Peekaboo!" is one of the Oobi shorts.
Oobi, Uma, and Kako are at the playground. Uma asks to play peekaboo, and the boys agree to. They cover her with their palms and then uncover her. Uma forgets what to do next, so Oobi whispers for her to say "peekaboo." She gets the hang of it and they repeat the game a couple times.
Kako wants to have a turn, so he walks between Oobi and Uma as they play the game with him. Oobi takes a turn and then notices the viewers. He asks if they would like to play peekaboo as well. The camera is covered and later uncovered, revealing Oobi, then Kako, then Uma. The kids laugh together as they finish their game and the episode ends.