Some people aren't using those microwaves to heat up a frozen burrito.

When you're at a convenience store and in a rush, you probably don't give a lot of thought to that microwave by the coffee pots. You heat your burrito or Hot Pocket and go about your business without thinking about what else might have been heated in there before.

Customers at a Florida gas station were probably doing just the same until the owner put up this sign:

Parul Patel had to put up the signs because people were using the microwave to warm up urine samples. Her store is located near two drug testing centers in Jacksonville. She says some people come in to warm the urine that isn't theirs so it seems fresh. Click the link above to watch an interview with Patrul.