Yogurt mule
A person or persons who use their anal passage to transfer illegal or contraband into jail or prison. Also they can be existing inmate that transfers items form cell block or from cell to cell. They can be an inmate or a vistor.
An inmate will hide and transfer drugs by using his anal passage to contain the drugs from being found are called a yogurt mule. Often inmates are forced to spread their ass cheeks apart and searched for such items.