Now there's an obscure bit of humor...

http://en.wikipedia.org/wiki/Type_89_grenade_discharger

...Some Allied infantrymen mistakenly assumed that the grenade launcher was propped on the leg to fire and thereafter referred to it as a "knee mortar". However, any soldier or marine who tried to fire a captured Type 89 in this fashion received a severe bruise (and sometimes a broken thigh bone) from the hefty recoil.