What is the most unusual implement of war you have seen?

Probably the most unusual in my time was the Davey Crockett (nuclear device), a wired nuclear system to be used at Battalion level.

Body sniffers shape like jungle plants in Vietnam

Never saw them but people never believe me when I bring up the ill fated Soviet anti-tank dogs of WW2.

Oh wait... we had some JO's launch water balloons at another boat during a PASSEX, does that count?

There were always those stories about our seagoing forfathers using every thing that would shoot from a cannon. ANYTHING.

I remember we used to have a 40 mm hand cranked belt fed grenade launcher mounted over our aft 50 on PBRs (River Boats not the Beer). If you cranked it too fast it jammed. If you cranked it too slow it jammed. I always considered it next to useless. You usually did not have the time to get your crank speed right to make it effective. THe second I saw used effectively was C 4 wrapped around trees on trails. Made excellent Anti personnel devices. We also had two boats with a 20mm aircraft cannon mounted in tandem with the forward 50. Damn thing would cut down trees. Unfortunately it tended to turn the boat so you had to constantly correct.

Can Omlette with Cheese MRE count? Ain't nothing about it an omlette, and the cheese was questionable unless it was separate and you had the MRE bread

Dead animals and/or people used as catapult ammo and slung at fortifications during sieges