A fake $10 bill is now evidence in the felony forgery case that could land Syed Ali in jail for two to 10 years.

After our sister station KHOU's story aired Thursday night, viewers wanted to know how they could avoid ending up in trouble like him.

"You should inspect your currency before you use it," said agent Marvin Wright with the U.S. Secret Service. "But most of us don't."

Related: Man arrested after unknowingly using fake $10 bill

Wright laid out real money and counterfeit bills to see if we could spot the difference.

"They just feel different. If I were to hand you both of these notes without looking, you'd be able to pick out the real one," Wright said. "People who deal with money, clerks or tellers, they can tell you without looking at it if this one's good or this one's not."

That's likely how managers spotted the fake $10 at Taco Bell. But there are even easier ways to spot a fake.

First it's the color shifting ink. For example, on a $10 bill, the number in the lower right-hand corner is copper when you look straight on, but if you rotate the bill, that same number will look greener.

Next look for the watermark. In the new bills, the watermark is actually a replica of the face on the bill. Just put the money up to the light, and on a $10 bill, you should see Alexander Hamilton's face in the right-hand corner. If there's no matching watermark, then it's not a real bill.

Finally feel for raised printing. Real bills are printed differently. If you run your nail down the collar or jacket of the person on the bill, you should feel a raised texture -- not smooth.

"On the fake, it's going to feel flat, because it was done on a copy machine or printer," Wright said.

Wright says about 1 in 600 bills could be fake, so it's important to know what you're carrying to avoid situations similar to what happened at a Houston Taco Bell.