What kind of theme besides a luau for a backyard bbq?

I'm planning on having a barbeque for my husband's upcoming 39th birthday. I don't want to do over the hill (too tacky I think) and we've already had two luau themed parties in our family in the last year. What other themes can I go with, for decorations, cake, etc?

Beach blanket bingo! (bongo? ) C'mon Gidget! Do it for Moondaddy!

farming. Under rated, very easy and quite practical. (the barbecue, not the actual industry)

Cowboy cook-out, cruise ship buffet, hillbilly hoe-down. Wear jeans and cowboy hats. Use bandannas as napkins. Serve chuck wagon food: ribs, baked beans, corn bread and some Mexican dishes.

well you could do a baseball theme and make the cake look like a baseball or you could do a 50's theme..poodle skirts guitars all that kind of stuff..

sports theme... everybody can come wearing there favorite team jersey and u can have a sports themed cake
and since its the basketball playoff's basketball would be a perfect theme. but if he's not into basketball u can go with any sport.

There's always the cowboy/cowgirl theme, or the Ozzy theme seems very popular (throw another shrimp on the Barbey) or of course there's the BRITISH theme. you get someone to spray water all over you and your friends every five or ten mins just as the BRITISH bangers are just getting started to cook on the BARBECUE, (Ho gosh dear it's raining AGAIN) every one inside for tea and cucumber sandwiches (Ho a bit of TIFFIN)
Dr KNOWITALL UK Heee heee heee.