Why America's Next Top Model are many competitors to walk around the house in his underwear?

I saw a large number of ANTM different seasons and are always a couple of girls who always walk in his underwear. Jade is an example of one. I do not understand, I have a good body, but I would not do that (especially if it was on TV). person in my school so, I've never had roommates do, or just with friends walking down the underwear (and most of us are very comfortable with our body.) and other reality shows that I've never seen anyone do it. I do not understand.

Evaluations and they think they are hot.

ANTM Jade’s Covergirl Commercial