When I work on a freelance gig that doesn't require me to be at the agency (the best kind), I like to get away from the distractions of home and use whatever Starbucks I happen to be near as my local branch office. Inevitably, as you'd expect in an establishment serving coffee in cups bigger than apartments I've had, people will eventually have to make a trip to the restroom.
For some reason, when that time arrives, I'm the guy they always turn to and say, "Excuse me, can you watch my stuff?"
I usually give them a non-committal kind of half-nod that can be taken for a yes, but that I can use for a no if their stuff goes missing and we wind up in court.
I think it's flattering people think I have an honest face (if that's what they think) and feel like they can trust me with their $3500 MacBook Pros, Swiss Army backpacks and iPhone 6's for as long as it takes them to pee. But the fact is with one house, two kids, two dogs, three cars and having to finance all of them, I have enough responsibility in my life without being a security guard for your stuff.
Plus the assumption I'm going to give chase to someone who's made off with your stuff is flattering, but misplaced. The most I'll do, and only because my sense of right and wrong is so finely honed, is try to get a plate number if they're in a getaway car.
It's an odd thing to me how unlike any place else, Starbucks and other coffee houses seem to work on the honor system. You don't leave your car running at the post office and ask the stranger walking by to watch it for a minute while you run in an mail a letter. Alright, maybe not a great analogy but you get my drift.
Anyway, it doesn't matter how nice you ask - I'm not getting shanked just because you couldn't hold it anymore.
Why not just do what I do? Get up, confidently walk to the restroom, quickly do your business and get back to your table. Make the assumption whoever's about to make off with your things doesn't know if you're watching them from the line or locked in the loo.
If your stuff is gone by the time you flush, don't blame me. I told you not to ask.