The clicking sound one can make out of the corner of their mouth. Most commonly done in two click increments. Sometimes adults use this sound to discretely call each other to the bedroom for SKEECOO SKEECOO time. The good news is that this is not a hereditary bound trait, anyone can master it. I bet you just did it.
"Stop calling the cat Bill, Fluffballs is outside!"
"I know Marge, that clicking sound was for you, now get your kitty over here ..."