In article ,
dgk wrote:

Actually, the first part of the urine is likely to be a bit dirty as
it passes external skin and picks up the assortment of bacteria that
everyone has. When you give a sample for bacterial culture purposes,
you're supposed to use a "clean catch" technique where you miss the
first part and get the middle. If you're just going for a urinalysis
(chemical breakdown) then it doesn't matter.

The real problem would be related to what grows on the penny during
the time it is sitting in the urinal. Nice place for nasties from the
early part of the whiz, from things passing by on the air, etc.,etc to
grow. The last "deposit" is probably the least of your worries.