In the summer,the girls wear skirts with no underwear.
Girl, do you wear any underwear, I don't see any panti lines.
Variations of the word "underwear" exists to better express various degrees of understanding. For example, if one barely understands a situation, they may say "I rubber-band underwear" showing that they literally - BARELY underwear whereas someone who understands partially may say "I thong underwear."
Variations are left for the user to experiment with.