That’s the sound Ninja makes when he’s bouncing around in the guest bathtub. When I try to sneak over to peek through the doorway, he’s sitting still in the middle of the tub looking at me innocently with those huge green eyes. His noise is a little more like kaTHUNK kaTHUNK kaTHUNK, though.
Oh, well, off to chores. SYL.
Jake gets in the bathtub, too, and meows at the drain. Then he tries the mind-control, “You did NOT see me in the bathtub talking to myself!”