Mammy Johnson Share definition Flag This term originates in Knoxville, Tn by way of Jacksboro, Tn. It refers to getting caught masturbating in the morning by your mother when she is bringing you lunch money. Josh got Mammy Johnson'd this morning before work. I bet he's gonna have an awkward dinner. Mammy Johnson by Ashley P. March 30, 2009 0 0 Get merch