Marble Cake may be used as either a noun or a verb; however, in either context it describes the action of a man anally penetrating either a man or a woman and ejaculating inside of said person. Afterwards the person on the receiving end defecates. If the defecator is a man, he then masturbates into his own feces.

Finally, the resulting mass of feces and ejaculatory fluids is put on a platter and one or both parties partake of the "cake."

This is similar to Felching.

1) a type of cake made by partially mixing vanilla and chocolate cakes before cooking, to create a marble effect
2) inter racial homosexual anal sex

When a male drops a huge load on his woman's chest, then proceeds to spray his fluids in a circular motion, thus creating a marble-esque cake