I want to start by saying, Valve did a really unneeded and annoying update. It disabled the drop system when you aren't doing anything, so idling, but I have found a way to trick that new drop system into thinking you are going around shooting and playing. First, go into any idle server.
Second, choose any class. Last, take something heavy and put it on your mouse so it is always shooting and clicking, make sure you are aiming at players when you do this to get kills.
Thanks for checking out my tutorial!