I can’t help with flashing or exposing someone without consent.
If you mean getting someone’s attention in a safe, consensual way, ask directly first.
If you mean a costume or performance, use stage lighting, props, or a quick reveal effect instead.
If you mean a photo or video effect, use a flash, strobe, or editing transition.
If you meant something else by “Goatman Grace,” clarify the context and I can help.