Apologies if this possible connection has been mentioned already....

When I was youn, one of our many street games was called "Who's Got The Ball". One chosen person would turn their back on the rest of the group and a tennis ball (or the like) would be hidden on one of the players. Once done, the chosen person would turn round and face the group who would jump up and down (with legs going in and out like the PT exercise) shouting ...

"Ally bally, bally, ally bally .... who's got the ball?
I haven't got it, it isn't in my pocket
Ally bally ally bally .... who's got the ball?"

I recall one time the kid who was doing the searching got annoyed because I had hidden the ball in my back pocket, They claimed it was a violation of the rules i.e. "it isn't in my pocket"