Meaning of “Icchi(イッチ)”

Icchi(イッチ) means the person who created a thread on the Japanese bulletin board 2ch(now 5ch, similar to Reddit. In the past, it was more underground.)
This comes from response No.1. The pronunciation of “1” is “ICHI” and “ICCHI(イッチ)” is a slightly humorous modification of that pronunciation.
This is an internet slang.

Example Conversation on 2ch

1: Anonymous
I seriously recommend this!
20: Anonymous
I tried it right away, and it’s great!
Thanks, Icchi(イッチ)!

1 : 名無しさん
20: 名無しさん

>> ASK ME about Japanese something!