The “hidden ball trick” was something fielders in the early days of baseball loved to pull on unsuspecting baserunners. Basically, the fielder would go to the mound for a conference, the fielders would gather around the pitcher so the ball wasn’t visible, the ball would go back to the base with the fielder, who would then tag a runner who wandered off base.
It doesn’t happen much in modern baseball — per Wikipedia, the last time was in 2013 — but in the old days, when players were perhaps a bit less attentive to what was going on around them and fielders were a bit more interested in subterfuge, it happened quite a bit.