Ordering a Happy Meal from a McDonald's drive-thru in Pittsburgh made customers a lot happier than a regular cheeseburger ought to. The reason for the extra smiles is that customers were ordering more than a free toy; they were also ordering heroin.

Drug detectives arrested McDonald's employee Shantia Marie Dennis for allegedly selling heroin on Wednesday. They say that all customers had to do to score was stop at the drive-thru and say, "I'd like to order a toy," CBS Pittsburgh reports.

The arrest came after the District Attorney Narcotics Enforcement received a tip. Next, officers from North Versailles, McKees Rocks and Swissvale joined undercover agents to set up a "controlled buy" yesterday afternoon. An informant set up the transaction at the McDonald's.

During the operation, police received 10-stamp bags of heroin in their Happy Meal. Dennis reportedly had an additional 50 bags on her.

Dennis was charged with possession, delivery and possession with intent to deliver.

Here is how Mike Manko, a spokesman for the district attorney's office, says Dennis worked the fast food drug drive-thru:

After a customer said the secret phrase, he or she was instructed to drive to the first window. They handed over $82, The Post-Gazette reports. According to WTAE, Dennis put $80 in her bra and the remaining $2 in the cash register. The customer would then receive a Happy Meal box with a free toy and heroin.

After receiving their extra happy Happy Meal, the customer would drive away, skipping the second window.

It is still unknown for how long the operation was going or how many transactions were completed at the McDonald's.

"As an employer and a member of the community, the safety of our guests and employees is our first priority," Iftikhar Malik, McDonald's owner and operator, said in a statement to WTAE. "The allegations related to this employee do not represent acceptable behaviors and are not consistent with our values. As such, we take these charges very seriously and we are fully cooperating with the authorities. We are also conducting our own thorough internal investigation. For additional information, please contact the local authorities."

Dennis was working out of the McDonald's restaurant at 6361 Penn Avenue. It is located in East Liberty's Bakery Square.

Dennis is 26-years-old, and is from East Pittsburgh. She is the second McDonald's employee to be arrested for selling heroin in the past two week. The first came from Murrysville, Pa, which is just 20 minutes away from Pittsburgh.