Haha! I'm glad I'm not the only person who thinks about things like this!! XD
I honestly don't know.......probably soap? There's not point in spending money on shampoo when anda could easily just use your soap atau mandi, shower gel!
Shampoo. I would feel discriminated against if i was bald and didn't have the right to use shampoo.. But they might use it because it makes them feel like they still have a full head of hair?