Essential game night prop: air horn.

Transcript

Han: Right, now we spray the pheromones on our suits.
R2-D2: Forget the pheromones.
GM: For that matter... What pheromones??
R2-D2: Let's work out where we need to go. I have the Peace Moon plans. I programmed some back doors last time I was here.
GM: Uh... you were never here.
R2-D2: Sure I was. Twenty years ago I visited the Moon for the first test firing.
GM: Which never happened. It was still being built.
R2-D2: Right. Allowing me to install the back doors.
GM: Hmm. Okay then. You installed some back doors twenty years ago. Go ahead.
R2-D2: Sweet. I plug into an access port.
Obi-Wan: Wait! No!
[SFX]: Whooop!! Whooop!! Whooop!! Whooop!! Whooop!!
Obi-Wan: Please don't tell me you were expecting that to work.