An extreme sport in its early stages, but still sweet fun. Mattressing involves finding a mattress with wheels on the underneath (quality may vary, but if you use the small wheels mattresses come with then they will beak which makes it all more interesting) and a steep hill with a road on it. Take the mattress up to the top of the hill and from a running start jump onto the mattress and roll down the hill. Normally crashing into the gutter is unavoidable. Avoiding crashing into cars on the street is desireable. This activity can be greatly improved by any of the normal stuff ie. A good mate, booze, comfy mattress, sex (not with good mate unless good mate is of opposite sex, but 2 girls would still be OK).
Pimpin' up your mattress is a good idea.
"ive got two mattresses with wheels and a case of beer"
"sweet dude, lets go mattressing"