Scanty and Kneesocks, along with Corset, appeared as a proper rapping group in Panty and Stocking Vs. The Powerpuff Girls: The Unshitty Version; this article is specifically about their original cameo, however.
Information on the CameoEdit
Scanty and Kneesocks are the main antagonists of Panty and Stocking with Garterbelt. They are a pair of demonic sisters and rivals to the titular characters along with their master Corset. They also have a pet named Fastener, hold a strong penchant for "rules", and are known incestuous lesbians.
Well if they get to join this battle, then so do we!
Step aside, skinks!