Oof means Courtney baf or a meme cool kid way of saying oh dear. Thei5pro loves to use this word and might be seeking therapy over the obsession of saying the word. Examples of using this word would be "is that a Courtney I see, oof" or "big oof I just stubbed my ear". The latter meaning is the meaning used more commonly and you should assume that people mean the second meaning. The word oof is thought to have originated from potatoes.