A generalization of "drob" could be likened to a slobbyness or lack of effort, but more commonly; is used to indicate garish bright clothing and/or feminine style make-up or fake nails/wigs which are blatantly fake. Generally a drobby dresser is not trying to hide ones gender but seeks to make it plain and obvious what they are.
"Drob" is also sometimes used to indicate that a transvestite who is trying to hide their gender, has failed somehow and in this sense is sometimes used to incorrectly identify a woman who looks like a man; who is trying to look a woman (another word for this last description is "unfortunate" or "unlucky")
Q. Is that drob?
A. Dude, that's a chick.
Oh look! Green and purple lycra in a tutu, that's drob... Like yo mamma.
Can be used to assure someone that something, certainly, has posed no problem at all.
Person B: Aw, drobs.