Haha, that EXACT thing happened to me today at school. Before class I had my laptop out and I was checking ebay, and the guy next to me saw an engine I was looking at and asked what its for. And I told him its for my RC car, and he gave me that typical "what, arent you a little old?" look, but then he realized they were "gas" powered and was suddenly a lot more impressed although obviously still a bit confused.