COD4 TDM
I was playing last night on Crash, one of my favorite levels, and I found myself upstairs in a building in the far corner of the map, surrounded by enemies. They kept coming in, maybe one or two at a time, and I got into a cycle of gunning them down, and then swapping my weapon for whatever they'd been carrying. I had the double-tap perk, so I ditched my Skorpion for an M4, and emptied that into the next wave, and picked up an AK47, and then a P90, before I was eventually taken down. That was pretty sweet.
A glory-moment from days gone by, on CS:S, that sticks to mind, took place on de_dust 2, when I was a CT trying to defend the (dropped) bomb in one of the bomb sites. Two terrorists came running in, and I had less than half a mag left in my M4. I emptied it, killing one, and I just discarded it, something I got into the habit of doing rather than switching weapons, reloading, etc.
The empty M4 sailed through the air, and landed *ON* the enemy Terrorist, who was using a Desert Eagle or something.
He obviously had the "switch to new weapon if more powerful" option turned on, because as soon as it touched him he whipped it out, and began the slow, tedious reloading animation, as I shot him to death with my USP.
It was totally unintentional, and I never managed to replicate it.