The phrase "Tiny Knife" is in reference to a popular TF2 artwork posted on r/tf2 on Feb. 22, 2022 where a class called The Spy from Team Fortress 2 (Hereby referred to as "The Spy") in the game Team Fortress 2 is drawn holding a knife that is smaller than it should be. A comment was made on a criticism of the drawing saying "Tiny Knife" reading as follows:
"May you please explain this? How on fucking earth was your criticism constructive all you said was essentially 'you drew this poorly' other comments literally did exactly what constructive criticism is, criticism that says what can be improved upon. I wish I didn't even get ropes in this, as your previous activity even in this specific subreddit makes you sound like a ultra-asshole. So for your 'mentally debilitated child' mind, don't be a dick in your criticism."
This reply also became a common copypasta spread among the community, often referenced in other artworks where The Spy is holding a knife which is smaller than usual.
The original tiny knife, goddamn magnificent.