play, frolic, sport
戲 centers on lighthearted, playful activity: engaging in fun, frolicking, or sport for amusement rather than serious purpose.
戲 combines 䖒 (a vessel or tiger-related element) with 戈 (halberd/weapon), likely suggesting a mock battle or ritual performance with weapons, from which the idea of play and sport developed. The exact historical development is uncertain.
The left side 䖒 looks like a decorated stage or mask, and the right side 戈 is a weapon. Imagine actors on a stage play-fighting with prop weapons: it's all in fun, just play and frolic.
For ギ, picture a playful geek (ギーク) in costume on the stage, swinging a toy halberd: geek -> ギ, and the whole scene is a playful sport.