Pee itself doesn't "go bad" like a carton of eggs, but it does become unreliable for testing. If you're desperate enough to stash a sample, use a sterile container, keep it cold, and test it within 8 hours. But honestly, the best advice is to just let your body do its thing naturally.
Or, you know, don't put yourself in a position where you're babysitting your own urine in the fridge. Dave learned that the hard way. He took his old sample to the lab, they called it "degraded," and he had to retest. He was stressed for a whole week. Not worth it, man.
In the end, your best bet is fresh, warm, and straight from the source. Think of it like a fresh cup of coffee. Would you drink week-old cold brew left on the counter? Probably not. Your drug tester feels the same way about your stale urine.
