When you enter a game of peak-a-boo with a child, expect it not to end until that kid is tired. Also, expect that kid not to get tired.
During work, one of the little kids kept covering his face and flapping his fingers open at me and Judy. We knew what he was doing, and we played along for a while. Only, when Judy went to leave, the little kid upped the ante: hiding behind racks and shelves of clothes while I worked and jumping up to surprise me. It was cute, for a while.
Then he started to run around, and when everything was quiet and I was putting up clothes, he'd run out from somewhere hidden in the store and yell really loudly, waving his arms like a mini-maniac.
In a small store, this gets awkward, especially since you were encouraging this behavior before.
I looked at him and calmly told him that it was quiet time, thinking that this is what adults normally did to me when I was younger, but orders only last so long on little boys. Peak-a-boo though? That's forever.