Microsoft had an Xbox event recently and brought custom glasses for the visitors to drink from, and from the look of it, they really wouldn't mind if you stole one. All of them are decorated with the text: "I stole this from an Xbox One event"
One of the people who obviously did just that and stole a glass is Ray Versus, who also posted proof on Twitter with the picture below and this text: "Indeed I did. @jeffrubenstein @blainh @majornelson @aarongreenberg"
Of course, this is common practice at events and hotels alike. We're not sure if it has ever stopped a would be thief or as in this case it only encourages them.