Peek a Boo

on
Understanding Object Permanence
Piaget notwithstanding.

Two children playing peekaboo
(1895 painting by Georgios Jakobides).

Origin: 
1325–75; Middle English piken  (v.); perhaps dissimilated variant of kiken  to keek

Can be confused: peak, peek, pique, piqué.

No point to this whatsoever. (the video that follows, getting my vote for the least likely to have a sense of permanence, or this post - whatever)