Have you ever noticed how the "non-nerdy type" will get that glazed-over look on their eyes when you try to explain why your plants are so green and lively? They just kind of nod and say um huh
I've had to stop myself a few times from going in to a scientific rant with my step-brother. He's not stupid, just a little slow.....(I think)
My favorite is the glassy look accompanied with the occasional nod and "Uh-huh". You know they have completely tuned you out then and you are just saying "Blah, blah blah blah blah..."
I had a great time (note irony) trying to explain to my family what I do. My sisters are clueless, but my mother got it, as soon as I told her I was "gardening", I just "garden" under water.