An order of a Big Mac, fries and coke may not be what it seems at one McDonald's in the Bronx.

The fast food restaurant in Soundview was closed by the Health Department after prosecutors say the night manager was selling cocaine.

Frank Guerrero, 26, is now under arrest.

He's accused of delivering the drugs by putting them directly in the bag with other food items.

Police say Guerrero sold drugs to an undercover officer several times during a three-month investigation called "operation off the menu."

Investigators say they searched his home, where they found more cocaine.

They also arrested his girlfriend.

"I can't believe this. I'm like what? Drugs? In the Ronald McDonald's? Come on, this is horrible. What can we do?" said one shocked customer.

"They're usually like really friendly in there - never had any issues. It's just like you local neighborhood McDonald's, so I'm just shocked," said another customer.

In a statement, the owner of the restaurant said the alleged actions of the employee are unacceptable and they are cooperating with the investigation.