Joke stolen from: Clean laffs

I walked into my sister's kitchen and found my nephew having a snack.

"Where's your mother?" I asked.

"She said she was going to have a shower. Just a minute, I'll see."

He stepped into the bathroom and flushed the toilet and a second later a sharp yell came from upstairs.

My nephew walked back out and said, "Yep, she's in the shower."