Got Rig Envy? Try Viagra DAVE BARRY Let's say you're a middle-aged guy. It's a Sunday afternoon, and you're planning to relax by watching a little football, defined as ''11 consecutive hours of football.'' You settle on the sofa and turn on the pregame show, and the first thing you see is a commercial for a pickup truck. This is followed by another commercial for a pickup truck, and then, for a change of pace, several more commercials for pickup trucks. Then there's about 45 seconds of men talking about football, followed by still more commercials for pickup trucks. At...