I have a few older exploits that would go nicely in a thread like this, but I should probably stick to the current stuff. Tale for another day.
Anyways, a good TF2-related moment comes to mind right now. The first was in a 2fort match, with me playing Soldier. A Spy and two Medic/Demo pairs had just taken down the other team's Engies, but they all died in the process. I managed to get to the front lines first on Soldier, but they had the workings of a defense building up again.
Cue the crockets.
Somehow, I manage to get three unboosted crit rockets in a row. First takes out a Soldier, Pyro, and Medic. The second finishes his Heavy buddy and a nearby Scout, and the third simultaneously gibs both Engies and their under-construction Sentries. Feeling like a missile-toting Rambo, I head up the courtyard stairs and down into the Intel area. Once I grab the intel, I hit my Buff Banner, considering it was charged by the crocket storm, and go up the ramp. I get smacked in the back by an Engie with a Southern Hospitality when I walk out, so I switch to my Equalizer, and when the bleeding wears off, nail him in the face with a crit swing and one-shot kill him. Now that my health is down to 50, the Equalizer's highest-level boost kicks in, so I sprint towards the gate with the speed boost. I manage to avoid a charging Headtaker Demo and finish him in two swings, then a Scout that drops down in front of me from the grate in one. From there, it seems that my team was busy holding them up to stop a full-scale attempt to kill me and save the intel. I run right out the front door unopposed, scoring the winning capture for the round. When alltalk came on at the end of the round, there was a LOT of screaming directed at me and my crits. Thus, my Black Box and Equalizer earned the name/description tags that I gave them.