The 'Pot-a-lizer'? The 'Weedometer'?

If you think all those lights changing colors at intersections are really pretty, and you wonder what the special occasion is, and you hear all those car horns blowing nearby, accompanied by screeching tires, and you wonder why there's all that traffic rushing through the intersections from the cross-streets while you're trying to get through yourself, and nearby pedestrians are yelling things like "Hey! Dumb-ass! Watch It!", and you can't figure out what they want you to watch, especially while you're enjoying all these pretty lights already, then you're probably 20 feet off the ground and rising, and you really ought to park that thing before someone T-bones you right into that store on the corner.