Like the experts say...

the urine that is to be tested must be of the correct temperature "Freshly and Actually Pissed Temperature".

I believe that is somewhere between 90-100 degrees.

depending on how long you're planning on keeping it in your shoe (a pill bottle? ouch) it may cool in the process and be too low a temperature for it to be considerd acceptable for testing.

im new here, but from what i see there are a lot of threads that may help answer your question on that one.

That being said, good luck. Im jealous of you and your access to a little brother