fawn
麑 centers on a young deer, specifically a fawn. It is a specialized character for a baby deer.
麑 combines 鹿 (deer) with 兒 (child), directly expressing the idea of a deer's child, a fawn.
A deer 鹿 with a child 兒 inside: picture a mother deer sheltering her little fawn.
For ゲイ, imagine a fawn playing a game of hide-and-seek: game -> ゲイ, as the young deer hides behind its mother.