Pull the grenade, throw the pin Achievement
Pull the grenade, throw the pin50
Killed a total of 15 enemies by holding cooked grenades
Hold down the thrown weapon button while you have grenades equipped and Deadpool will pull the pin and hold the grenade. Stand near some enemies when it explodes. Many enemies will die in 1 hit from this on easy. An achievement counter will pop up to track your progress as you get kills.