according to google translate, youmu has written たておつ="tate otsu"?
EasyV said:
Seems to be some internet slang.
It's the portmanteau of スレ立て (creating a [2ch or whatever imageboard's] thread) and お疲れ (thanks for your [hard] work). The latter is often abbreviated to 乙 (different kanji, same reading as the first two kana), and the phrase would become 立て乙/たておつ - thanks for setting up a new thread.