Wash your house away. Where were you? Where were you?

The story:

My friend was over and we were driving to her house yo drop her
off. In the car, this song came on and she started singing to it. I
joined her and when it got to this part, she started singing "Why'd
you have to wait?" while I started singing, "Wash your house away".
As soon as she heard me, she stopped singing, stared at me for a
couple seconds and burst into laughter. She couldn't stop laughing
until we got to her house.