Verified answer

Send him up in the attic to get you something, and then go in the basement and shut down the power, practice it first when no one is home to make sure you have the right switch. Put on the attic light and go down in the basement and shut what switch you thing it is, and go up stairs to check and see if it's off, keep doing that until you do get the right switch, you can have a friend with you.....and mark the switch that you know what one it is.

I once stood my vacuum at the top of the stairs, covered it in a black dressing gown and put a mask on it. I then switched the light off and waited for someone to go up. I literally blacked out laughing at my family's reaction to it.