Phone line on the edge of a nervous breakdown

When I was younger, my mother was dating my now step-father. He loves to pull pranks just as much as I do.
My older sister and I were home alone while our mom was working, when the phone rings. My sister answers it and has a nice man, Frank, from the phone company on the phone. He explains that due to all the recent rain, the phone lines are full of water and they'd be "blowing them out". Due to this, my sister was advised to put all the phones in the house in bowls so water wouldn't get everywhere.
Now, my older sister is very smart. I'm more of the common sense type. I just couldn't understand why she would do that. I mean, after all, wouldn't that cause electrocution?
Anyhoo, my mother gets home and wants to know what's up with the phones. My older sister explains it to her and boy did we all have a great laugh when we realized "Frank" was actually John.

I have another way better prank but if I told it, I'd have to kill you.