in 25 Years of Gaming I'm also pretty good at explaining the Games to Outsider without it sounding too...Nerdy
That got a lot easier for me when I realized that pretty much any hobby looks nerdy if you're not involved. Consider the following real world examples -
Model railroads - painstakingly building miniature terrain so you can flip a switch and watch a toy train drive along it.
Civil War reenactment - Dressing up in itchy wool uniforms, living in a tent, pretending to get shot and glamorizing an era when medicine involved leeches and sawing off limbs without anasthetic.
Fly Fishing - Hand tying tiny feather things to hooks so you can put on rubber pants and throw your carefully constructed toys in the water
Scrapbooking - I don't actually know a damn thing about this, but it just seems nerdy.
They all have an appeal to the people who do them, all require a big time investment and all make you look pretty silly to people not involved.