Learn an amazing grilling or smoking technique
Dig a pit and make some barbacoa. Smoke a pork butt in all its Carolinian glory. Hell, get some swords, stab some sirloin, and meet at the confluence of Fogo de Chao and Medieval Times. Once people identify you as a person who goes beyond just putting crap on a grill and waiting, yours will be the cookouts everybody looks forward to.
Invent your own yard game
The world is your Calvinball, and if there's a game that only gets played at your house, your house becomes the arena. Just be sure to print out some rules to make it official.
Bottle and label your BBQ sauce
Choose your style, then put your own twist on it. Or just re-bottle some other BBQ sauce. Nobody's gonna know the difference. Except maybe all those chefs you invited... though they're probably on the Slip 'n Slide, so whatever.