How do you know when your child is nearing the teen years...

I took the kids to the store and needed to get a few t-shirts for myself. Just plain t-shirts, nothing crazy. I picked up a bright green t-shirt and he says, "Mom, you can't get that. It would embarass me! Besides, it wouldn't match you eyes." I am thinking, my eyes are green??? So I went with a camo. green to save future embarassment.