i really love singing in the shower.
I do too!  A lot of people like it because the hard surfaces create great acoustics
yes! It kinda makes me feel like i sound better in a shower
The first reports of people singing in the bathroom are from multiple centuries ago
What? That's insane :) I guess singing in a shower isn't so rare
Not at all!  Some professional artists have actually recorded songs in bathrooms
NO WAY! Do you know who?
Bjork and Weird Al both have recorded in bathrooms
i can see Bjork doing that. She is so strange and misterious to me
and depth."
This habit was reported (with an attempt of explanations) centuries ago. For example, Ibn Khaldun in Chapter 1 of his "Muqaddimah" writes:
The bathroom singer is an ironic reference to mediocre or amateur singers.
Jon Anderson had tiles installed in the studio, to simulate the echo effect of one's vocals in a bathroom.
This effect was not used only by singers. Paul Simon wrote:
"Weird Al" Yankovic in fact in 1979 recorded his first single,
Bathroom singing
Bathroom singing, also known as singing in the bathroom, singing in the bath, or singing in the shower, is a widespread phenomenon. 
Many people sing in the bathroom because the hard wall surfaces, often tiles or wooden panels, and lack of soft furnishings, create an aurally pleasing acoustic environment. The multiple reflections from walls enrich the sound of one's voice. Small dimensions and hard surfaces of a typical bathroom produce various kinds of standing waves, reverberation and echoes, giving the voice "fullness