Flickr user MRaichelson
Funny money is no joke.

Counterfeit bills are on the rise along the South Carolina coast, and police are advising retail stores to be on alert for any funny money — and you might want to be sure you don't accidentally get some in change.

Part 1: Detect behavior

The Beaufort County Sheriff's Office has sent around some tips on behavioral detection of those using fraudulent money.

It is especially important for business owners to make their staff aware of how rampant cash fraud has become due to the aid of advancing printing technologies. When cash is tendered as payment, the receiver should look for the following behaviors as possible red flags:

• Customers who appear to be in a real rush to get through the transaction even when it is a high ticket item.
• Abnormally low interest in the actual product, perhaps even indifferent to its size, such as in the case of clothing.
• Failure to make eye contact and/or frequently glancing at exits.
• Passing an abnormally large number of low denomination banknotes, i.e. twenty $5 bills for a $100 purchase. 

Part 2: Detect bad bills

This video's kinda rough, but it has lots of good tips, like detecting bleached and re-printed money.

Here are some more tips from the Secret Service:

• Look at the money you receive.
• Compare a suspect note with a genuine note of the same denomination and series, paying attention to the quality of printing and paper characteristics.
• Look for differences, not similarities. 

Portrait: The genuine portrait appears lifelike and stands out distinctly from the background. The counterfeit portrait is usually lifeless and flat. Details merge into the background which is often too dark or mottled. 

Federal Reserve and Treasury Seals: On a genuine bill, the saw-tooth points of the Federal Reserve and Treasury seals are clear, distinct, and sharp. The counterfeit seals may have uneven, blunt, or broken saw-tooth points. 

Border: The fine lines in the border of a genuine bill are clear and unbroken. On the counterfeit, the lines in the outer margin and scrollwork may be blurred and indistinct. 

Serial Numbers: Genuine serial numbers have a distinctive style and are evenly spaced. The serial numbers are printed in the same ink color as the Treasury Seal. On a counterfeit, the serial numbers may differ in color or shade of ink from the Treasury seal. The numbers may not be uniformly spaced or aligned. 

Paper: Genuine currency paper has tiny red and blue fibers embedded throughout. Often counterfeiters try to simulate these fibers by printing tiny red and blue lines on their paper. Close inspection reveals, however, that on the counterfeit note the lines are printed on the surface, not embedded in the paper. It is illegal to reproduce the distinctive paper used in the manufacturing of United States currency.