on a ladyboy (ie her ****).
Panties, or underwear are meant to keep personal body odors contained. It is understandable that some people find it erotic, but the lacy stuff is a side-line. Underwear was/is meant to contain smells.
I really wonder how a pourous fabric can hold back odors? Think about it, when someone farts in public they are usually dressed, and actually wearing more than panties, and people still smell it.