A few weeks ago we were just about to leave the house to go out to dinner when I noticed DS 11's hair looked wet. I touched it but it was dry.

I asked him, "When was the last time you washed your hair?" He couldn't remember although he showers every day because he gets sweaty from football practice.
We were in a big hurry so I did the old hospital trick of putting baby powder in his hair and then rustling it around so that the powder would soak up the grease and his hair would not greasy.
Fast forward a week later. I smelled the faint scent of baby powder in the kids' bathroom, but didn't have time to think about it. The next day I see a container of baby powder on the sink. I put it under the sink as I was cleaning. A few days later, the baby powder is back out on the sink.
I'm sure you all can guess what he was doing.

He had decided he no longer had to wash his hair and all he needed to do was put baby powder in it when it started to look greasy.