Those first games where you will rush mid on de_dust2....hell you'll just run everywhere, plus crouching and spraying and praying EVERY time. xD
The most recent screw up I did was actually in CS:GO, I was playing on cs_assault in office watching the vents. I killed someone trying to enter office and I drop my SMG in order to pick up their M4...but it inadvertently fell off the side of the platform. I also double tapped the drop weapon button by accident so I dropped my SMG and pistol down over the side as well! At this point, a CT drops down the vent to find a very confused me wielding only a knife....very embarrasing. It was a competitive match as well.