A food enjoyed in the ghettos of the Dirty South while growing up. It is made by spreading mayonnaise on one slice of white bread and then covering that slice with another. Often accompanied by some sugar water to wash it down.
The sexual act in which the male bangs the female in the doggie-style position and upon ejactulation, releases his semen between her butt cheeks and mashes them together, thus creating a medley resembling that of a mayonnaise sandwich.
That bitch didn't want me to cum on her face, so I gave her a mayonnaise sandwich