Classically refers to having a large chest, but in this slang context, it adds to the rhythmic "crusty/dusty" rhyme.

Below is an overview of its origins, usage, and cultural context. Slang Etymology and Usage

: This alliterative triplet is frequently used together to describe someone who has perhaps stayed at home too long, hasn't done their makeup or hair, or is generally "looking a mess".

: Sometimes used as a "call out" or lighthearted insult regarding someone's effort or lack thereof in their appearance. Cultural References