Person/peoples who takes "ratchet" to a whole other level, meaning they are beyond dirty, nasty, and/or ugly. They are foul to the fullest extent, and they rep their foulness with loud, boisterous pride.
It can be used to target a specific individual:
"Calm the fuck, you fucking ratchepotamus."
It can be used for an outta pocket situation:
"She is so wrong for that! On the real, she's a straight up ratchepotamus"
It can be used for a whole group of fired up ratchets:
"Somebody tell these ratchepotami to calm the fuck down."
When one is so bad, or ratchet looking, that all they can be compared to is a pool of ratchet-ness.
Bob: It's time to leave for the restaurant!
Natalie: But I'm not ready yet!
Bob: Well, we need to leave now!
Natalie: I'm not ready! Do you want me to look like a ratchpool!?