What's undie color you wear today? (Fantia)

Can your friend ask you what's undie color you wear today? 
I think we may have one or a few friends who ask you like this. Or maybe no need to ask because when you change the cloth in the same room we can see each other. lol 

Anyway, these boys are a close friends so they may do something that others won't do. xD 
Enjoy~