Facts submitted by people more qualified than me!
Tor Tor : "The first unusual ever unboxed in tf2 is actually a circling peace sign stout shako? Apparently it is and the owner of it is seeling at a super high price and he has been offered quite a lot really."
Kirby Gamez : "You can use the Ubersaw and Amputator's taunts by alt-firing"
Sgt. Devel : "The syringe gun also used to spin :) same with grenade launcher I think (I know syringe gun)"
(G.E.W.K) Pillzman's Fox : "As a medic main, scouts can gain additional jumps by hitting themselves (idiots) with the Boston basher"
Overlord : "The fastest way to get a level three teleporter entrance at spawn is by switching to eureka effect, placing the entrance, switching to jag, upgrading it, then switching back to your favourite wrench."
Overlord(again) : "You can use dispensers to block doorways so spies can only get through by destroying them. If you place teleporters on top of stairs, spies have to jump over them. If a spy flees into a small room without exits, instead of going in after him, just keep standing in the only doorway so he can't get out, and shoot him. If you trigger his dead ringer he still can't get out."
Nodspine : "The Kritzkrieg f*cks the quick-fix. The QF's pathetic overheal is nothing against guarantees crits"


And special shoutout to Mesmerizing Mannered Musketeer for correcting a lot of my mistakes!