Your going to need: Tf2, A sever That you own, and Friends that want to play Tf2

You're going to need a Map with a Inside area and Outside Area
Next get all Of your friends Into the Inside area of the map
Then Open The dev console *If you don't know how to activate that then Go into options Then go to controls,Click Advanced Then click "Enable devolper Console" Then bind a key and press it*
Now Do a command called CreateHairball This will spawn The Nightmare I had experienced While Testin'
the dev console. Now Spam it Then tell your friends to come outside Then Listen to there Screams of terror Whilst They Run back Inside Or Hide Or call you names

I hope this little joke went well if you don't understand then contact me on my profile or comment below :D