In Red Orchestra, when I fired an MG34 from the hip across the field of that map (I forget what it's called) with the Komsomol quarters and the Basement Building, hitting a prone guy in a bunch of rubble, with what had to be a headshot, in a few rounds, with reasonably low bullet spread. That was awesome. Also walking around in that trench map with an MG34 from the hip, repeatedly killing Soviet soldiers, even SMG soldiers who tend to roflpwn in such situations. I <3 hipfiring machine guns.
Also Red Orchestra, on some farm map, I walked into a small house with a Mosin-Nagant and was about to go upstairs, when I saw a German entering the door beside the stairs. I shot him from the hip, killing him. I then turned around and saw another German lying on the ground in a hole that had been blasted in the wall, and shot and killed him too from the hip. Then I got up the stairs, aimed out the window, and killed someone about 20-30m or so away with one shot. I seriously stopped there for a moment and said "what the fuck?". It usually never goes so well.
And one other time, I was crouching (also with a Mosin-Nagant) behind the sandbag wall at the end of the Anichkov Bridge on the Leningrad map, just firing at the opposite end of the bridge, when I suddenly hit someone who was apparently lying prone on the rubble at the other end, over 100m away, which got me an achievement.