ホロン部(horon bu) means　滅ぶ(horo bu=be ruined,fall).
A Korean agent tried to type "nihon ha horobu"(日本は滅ぶ), but he typed "nihon ha horonbu"(日本はホロン部) by mistake.
Since then 2CHANNELers call Korean agents "ホロン部".
So, ホロン部 makes no sense in itself.