This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

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n. The act of looking out suddenly, as from behind a screen, so as to startle some one (as by children in play), or of looking out and drawing suddenly back, as if frightened.

n. An alternate withdrawing or concealing of the face or person and sudden peeping out again in a playful manner or in some unexpected place, often resorted to as an amusement for very small children, and generally accompanied by drawling out the word “bo” when concealed, while “peep” is abruptly enunciated on reappearing: as, to play bopeep. In the United States more generally known as peek-a-boo.

n. a game played with young children; you hide your face and suddenly reveal it as you say boo!

"All run-away sheep bound back bopeep, trailing their teenes behind them."

child's game   

Jeep    Peep    Streep    asleep    beep    bleep    cheap    creep    deep    heap