Assuming the game doesn’t get rained out, the Nationals are offering $3 off any ticket worth $10 or more to fans who take Metro to tonight’s game, in honor of Earth Day. All you have to do is show your SmarTrip card or paper Metro farecard at the box office to receive your discount. And no, those of you who already bought tickets can’t show up at the box office and demand $3—the ticket promotion is good on day of game sales only.