Steal this ad. No really, it's fine. No one will yell, "Stop, thief!" And even if they do, you're in the clear.
More than 100 New Yorkers recently took jetBlue up on its offer of free flights and other swag by ripping off 181 bus shelter ads across the five boroughs. They were right there in plain sight—all you had to do was deface public property to get them (though no glass-shattering was required).
It's tough to be discreet with a poster-sized coupon tucked under your arm, but the locals didn't seem to care.