I have one When at least 5 people have come one put on a label that says "Cave Johnson" and say: "When Life gives you lemons, don't make lemonade, make life take the lemons back, do you know who I am, I'm cave Johnson, Make life rule the day you gave cave johnson lemons, I'll get my engineers to build a combustable lemon that blows your house down." I just had to put that down
I just thought of another one. Act like Wheatley and then when 3 people get on start acting like Glados. After that run around saying "Combustable lemon" and then press all the buttons on the elevator.