How about this? http://steamcommunity.com/sharedfiles/filedetails/?id=296069621I saw this on another server and absolutely loved it. Its a 1-use traitor weapon. When fired, a loud noice will be heard and +- 2 second later a rocket with headcrabs will land on wherever you pointed it. Great for taking out groups. Only works on maps with an open sky like a certain minecraft map with a lighthouse.
http://steamcommunity.com/sharedfiles/filedetails/?id=258844685&searchtext=headcrab+launcher+ttt
The moment you load it, people can hear it.