I have no idea about a graphic for this, but what about something like:
Tired of all the tall tales from your fishing and golfing buddies?
Become an AirVenture Fliar!
No fabrications - No Exaggerations!
All perfect landings right on the DOT!
or
Any pilot who tells you they made a perfect landing their first time at AirVenture Oshkosh will lie about other things too!
or
You can travel the world to see all that aviation offers, or
You can come to AirVenture Oshkosh and see it all here!
Yeah, yeah. 800,000 people and 10,000 aircraft of all types. blah, blah.
I come for the Brats and Beer. It's Wisconsin, isn't it?
or
Flying into AirVenture Oshkosh for the first time is like going from go kart racing to the Indy 500, but without the drivers meeting... oh, wait. There is that NOTAM thing...
or
Anyone who says all aircraft look alike has never been to AirVenture Oshkosh
or met Burt Rutan...
or
The only dummies at AirVenture Oshkosh ride in with Jeff Dunham.