Counterfeit bills are a major problem for retailers and banks. Spotting a counterfeit $2 bill is especially difficult because it does not contain many of the standard security features of larger bills, such as watermarks and color-shifting ink. However, there are several things you can check to ensure the bill you have is genuine. If you have any doubt, refuse it and ask for something else.
Inspect the portrait. It should be a picture of Thomas Jefferson.
Feel the paper. Real bills are printed on "paper" that is actually made of a combination of cotton and linen. It should feel somewhat like cloth, with a slightly stiff texture. If it feels like a smooth piece of printer paper, that's probably what it is.
Feel the ink. Real bills are printed with a process called intaglio, which leaves slightly raised ink on top of the bill. You should be able to feel the textural difference as you slide your fingers from a blank portion of the bill onto lettering.
Look closely for red and blue fibers embedded in the bill. This security feature is often ignored by counterfeiters or printed onto the paper rather than being embedded in it.
Inspect the printing. Real currency is printed using ink on metal plates, resulting in sharp, unbroken lines. If the printing on your bill is faded, blurry or uneven, it was likely created on a printer.