Receding Hairline

Alright, listen up, genius. This joke is saying the dude's hairline is receding so far back it's like the Giant character from "Clash of Clans," whose head is HUGE. The joke is that the hairline is so far back that even a Giant from Clash of Clans would be jealous of the real estate on this guy's forehead. You probably have never played the game, based on your hairline situation.