Whether you're into Arbor Day, old-timey trains or Elvis, chances are there's a stamp to commemorate your special interest. But the federal government is now distributing a stamp for a different kind of enthusiast -- lovers of phone sex.

The U.S. Fish and Wildlife service said Monday that 3.5 million federal "duck stamps," which must be bought and carried by waterfowl hunters, have been affixed to a card bearing a misprinted number that leads callers to a phone sex line promising "girls who turn you on." The card unfortunately transposes two digits from the correct number, 1-800-STAMP24, so that it dials 1-800-TRAMP24.

Rachel Levin, a Fish and Wildlife spokeswoman calls this "an unfortunate typographical error" that her agency "really regrets." However, the agency plans to continue to provide the stamp to eager philatelists (that's a stamp collector, perv), because it would be too expensive to reprint them.

We've been known to pinch a few pennies ourselves, but it seems like it might be worth the extra dough to keep a simple change of letters from turning your "duck" stamp into ... well, a different kind of stamp.