Hair is a fairly common way to check for drugs, specifically weed. I've never heard of it being done at an airline, but it is common in other industries.

I heard of a guy who tried to beat the system by removing all hair from his body, even eyebrows. He forgot the one spot he couldn't see--his bung hole.

He got fired--and rightly so. If you smoke weed, I don't want to fly with you, and I don't want to ride in your cabin. Get a job at a gas station or surf shop.