sponge gun
n.— «The officers used something that is commonly called a sponge gun it’s a less than lethal weapon that we have. The weapon was deployed in an effort to avoid having to shoot this man.» —“Santa Maria Man Threatens People With Large Knife” by Carina Corral KSBY-TV (San Luis Obispo, California) Apr. 24, 2007. (source: Double-Tongued Dictionary)