>>213972350
I think it is better a Japanese person comes up with insults for their language, but I gave it a try.
お糞呂 おふんろ
Best I could come up with in two seconds is poop bath, I'm sure you've seen someone spam the gifs of indians bathing in holy cow poop.
Another common 4chan insult is streetshitter, so you could try to use that as well, it is more inclusive than jeet which is pretty much only used for indians.

I am not an edgy person so I am sure some hardcore racist that crossfrequents /jp/ and /pol/ would come up with something more intense.