a type of urinal, the kind you might find in most male bathrooms. a tuba is the kind of urinal that is lower to the ground for midgets, and an inconveniance for tall people. it usually has the most bacteria on it, so cotton swabs can be used to test for this. occasionally mistaken for a musical instrument.
Abigail: Emily, we just tested the tuba for bacteria and man is there a lot!
Emily: What, you mean like a urinal?
The tall man was at a disadvantage using the tuba urinal.