All safety concerns thrown aside. Take your car to an open lot away from light poles and curbs. Quickly get up to 35 mph and press the brake pedal as hard as you can. If your tires start squeeling, smoking or leave big black mark behind you, you DON'T have ABS. When you slam on the brakes, if your brake pedal feels weird and makes a humming/vibrating noise you have ABS.

I think looking at your dashboard for the ABS light is a better idea.