Talk about a party hat! You'll never have to go looking for a bottle opener again (well, unless you're the sort who looks for house keys for an hour only to find that they're in your pocket). The Guinness Bottle Opener Baseball Cap has a metal hook right on the brim to tear off caps, and it's officially licensed by the beer company for good times.
The cap sells for $25, which is pretty decent. Still, Guiness seems an odd choice for a tailgate. That, and you may want to refrain from tossing it up into the air during big plays, or your friends may start calling you "Oddjob."