Trolling in Garrys mod (which you can buy off of Steam, a free sortware,) is a lot harder than trolling in other games. In garrys mod trolling is trapping your freind in a box or put him in a hole or even making him do something that is in a way to trap but not kill the apponent. Also the apponent cant know about the troll or it will not work.
This is an image of some ways of trolling on Gmod...