You can smoke and go to the local CB Discount (If you have those stores.) Or a gas station and ask to buy a quick fix. (It's a little box they keep behind the counter, its fake piss, it comes in a little squeeze bottle, your employer can't legally check your pockets so you should be fine.
Here is a list of stores that sell quick fixes: I can't find a store locator for you to be exact, just go to a local head shop and ask for a quick fix and if they don't have it just ask if they have any synthetic pee.
Or you can buy it online:
http://www.quickfixurine.com/
Hope I helped!