the common fire extinguisher. Face it, you're dealing with close quarters. Spray someone in the face and they are effectively blind. You can then easily beat the crap out of them with a blunt object. You also have no chance of shooting a hole in your hull. Next best is a cricket bat or an ice axe. My favorite would be the DMM Predator. The gear review by Mainer, Steven King will send chills up your spine:

This is not the sort of gadget to inspire nursery rhymes. I look at the DMM Predator ice ax and I think of murder. I take it out into the garage, find a piece of scrap wood, and drive the pick end into the grain, trying not to envision how easily this same tip could penetrate the skull and skewer the soft gray matter beneath. It makes a solid, satisfying chuk. This, I believe, makes the electroshock devices, the cans of pepper gas, and the ninja throwing stars in the pawnshop window look minor league. You could do some big damage with this. Real big damage.
The pick end is sharpened along the top and pointed at the tip. It is serrated beneath, presumably to keep it from slipping out once it's been plunged in, and when I examine the holes in the wood, I see that they are not the punch-points I expected--like a child's oversize, drawn periods, but lozenge-shaped-- --like cough drops.
Looking at these holes, I am helpless not to imagine them peppered over the human body. I keep seeing the ax swung at the gut, the throat, the forehead. I keep seeing it buried all the way to its 11th serration in the nape of the neck or the orbit of an eyeball.
Boy, I think, you are one sick American.
Or maybe I'm not. Like many tools--hammers, screwdrivers, drills, augers, and chisels come to mind--the Predator ice ax has a certain gallows fascination, a bleak beauty with a sternness so extreme that it seems almost neurotic. But study it and you see that there's no part of the ax that doesn't work, from the rough-hewn butt end with its wrist-loop strap to the arched line of the handle to its wicked, burrowing tip. I'm not sure what the thing on the other end is for, the piece of metal that looks like Paul Bunyan's bottle opener, but I'm sure it has a clear purpose, which those dedicated enough--and mad enough--to put their lives at risk climbing mountains and ice falls readily understand and utilize.
This brings me to a new conclusion: What I really feel when I hold this in my hand isn't so much the possibility of murder as the gravity of mortal things. It speaks to me of the vulnerability of human flesh, but also of the resilience and determination of the human mind: Lying on my desk, it whispers, "If you need me, I'll be there. If you need to hang all 215 pounds of you off me, I won't let go--if, that is, you plant me deep."
I have no plans to go climbing; I get vertigo when I ascend to the top of a stepladder. But I keep the Predator under my bed. Why not? One never knows when one might need a good tool, the sort of thing that might make the difference between life and death.