A flash grenade, also called stun grenade or flashbang, is a type of grenade with a very bright light when it explodes. Deadpool attempted to use one on the Hulk. When Wolverine distracted the green giant Deadpool surprised him by shoving one in his mouth. It went off and caused a large cloud, but Hulk simply emerged angrier than ever. (Hulk vs Wolverine) When S.H.I.E.L.D. recruited Wolverine to engaged the Hulk once again he used a gas grenade on him. This time it worked and Hulk was knocked out and turned into Bruce Banner. ("Wolverine vs. Hulk")