What can I do in the bathroom?

Hint 1 of 10:

This game is realistic, but not *that* realistic.  Look for evidence.

Hint 2 of 10:

The middle stall is the key.

Hint 3 of 10:

The toilet is what most people want a stall for.

Hint 4 of 10:

A toilet can be used to hide things.

Hint 5 of 10:

Where can you hide something in a toilet.

Hint 6 of 10:

Lift the lid off the back!

Hint 7 of 10:

Look inside.

Hint 8 of 10:

Get the gun.

Hint 9 of 10:

Replace the lid.