According to both the McDonald's reps and the distributor of the spray, just the sight of "DNA" on an anti-burglar sign is often a strong preventative measure. Criminals, say these folks, readily make the connection between "DNA" and "getting caught for your crimes," even though in this case the DNA is no more or less effective than, say, ultraviolet ink. Says the distributor about DNA (which it also sells in grease form), "No one really knows what it is. No one really knows how it works." Hence the sign on the front door reading "You Steal, You're Marked" (though it's worth noting that a patron of the restaurant, when asked, said she did not notice said sign).