Probably the first and only experience we will ever have in our lives concerning environments with perfect acoustics... no one can deny that the echo from the bathroom's tiles +++ electric heater noise is an incredible natural auto-tune.
What is the most played song in your shower concerts, IF you sing in the showers?
I have an addictive preference for any song that has a repetitive chorus like Brite Lites, Lizzy Grant or Universal Traveler, AIR's. But in reality, generally, the normal thing is that I sing any song whose lyrics I know and can make some crazy VaRiAtIoNs.
Woe to the neighbors