A massage performed using an erect penis as the stimulating device.
Source: "Someone You Know" by Gary Zebrun, Alyson Publications, USA, 2004, pg. 81.
"He tried to turn me over, but I resisted. He tried to put his cock into my mouth, but I wouldn't surrender. So he rubbed it against my face and up and down my chest until he spread cum from my neck to my navel -- a Princeton rub."