Make up a Grenade.

[Booze Zombie]

A grenade that releases sexy pheromones.

 

[blindthrall]

The gay grenade. Turns armies into piles of man-love.

The monkey grenade. It's just a poo grenade. What do you want? An ape invented it. Requires the invention of the soap grenade.

Or what about a grenade that's compressed carbon monoxide? It fills up low areas like trenches, suffocating everyone in them.

A leech grenade. Just gross. Like a vomit grenade.

What about an entropic grenade? Everything in its radius experiences time faster than its surroundings, and within minutes is dust.

 

[MattZero]

I would invent a grenade that induced a state of schizoid paranoia in everybody around it and every couple of minutes afterwards it would let out a quiet skittering sound. They would eventually all kill each other.