Body Paint: Water Based

Water based body paint is just paint, in liquid form, or you can buy it in a solid form, and use water to activate it, then apply it.  The most common way to apply it is by airbrush.  Although it dries very, very fast, there's a huge chance it will rub off at the first signs of sweat.

For applying the water based paint, you could use brushes, which lets you get more detailed.  Some have used sponges, however they tend to soak up most of the paint.  But the easiest, and fastest, way to apply water based body paint is by airbrush.

Pros:
Water based paint drys incredibly fast, usually in about 1 minute.  It is also a cheap product, you can get a 1 ounce squeeze tube for around $3-4.  For removal, you don't need any makeup removers, just some soap and water.

Cons:
It is reactivated with water, meaning it can rub off easily with sweat.  If you were outdoors, in the summer, it wouldn't last long.

If you want something short term, where you won't be in hot environments, water based body paint would work for you.  It is also great to use on kids, because it dries so fast and kids don't tend to sweat as much as adults.