I cracked the code! Nate has been making a gesture for days that was clearly a sign...I just didn't know what it meant. He would repeat and repeat it and I would sit there dumbly. Ugh. The exchange would go like this:
This went on over the course of several days until finally he made the sign outside today. And I heard it - A LAWN MOWER. "Lawn mower? You hear the lawn mower?" YES, he nodded enthusiastically. Relief in his eyes. Finally, the idiot mommy understands! I made my super realistic lawn mower sound to confirm. YES, a bigger, even more enthusiastic nod.
I've heard anecdotal tales that babies can make up their own signs. And now Nate is doing it. He has been turning the gestures we naturally make while speaking into his own "signs" lately. He points to his ear to say "HEAR," mimics brushing his teeth to say "BRUSH TEETH" and mimics brushing his hair to say "BRUSH HAIR." It turns out this was just another example. He has probably heard lawnmowers running every day this summer. And when he would look at me with interest, I would explain what it was and act like I was pushing a mower. He turned this into a one armed gesture. Ta da! Lawn mower.
Made-up signs are known as "home signs." They are fine to use as part of the baby sign language repertoire. Like the ASL signs, they help Nate to understand the meaning of the word and to increase his vocabulary. I'll just have to remember that it's a home sign and not an official ASL sign when I go around asking all the local deaf teenagers to mow my lawn. Who knows what Nate's sign really means.