Giggler

Giggler is a speedrun trick in Metro Kingdom that involves performing Mechawiggler Escape using a damage clip, collecting the Inside an Iron Girder Power Moon, and then returning to the fight, all while Mechawiggler is in its invulnerable phase. This effectively eliminates the time that is normally required to navigate to the moon later in the route, since the player must wait out the boss's invulnerable phase regardless. The name is a portmanteau of "girder" and "Wiggler".