Porn Legend Mary Carey -- Dwight Howard's a Human Tripod

Time for "TALES FROM A PORN STAR" ... starring porn legend Mary Carey.

Today's topic -- Which pro athlete would make the best adult movie star?

Mary -- an expert in the subject (she's starred in more than 100 films and was recently inducted into the AVN Porn Hall of Fame) -- says only one name comes to mind ... NBA star Dwight Howard.

And why is she so confident? Well, Mary has one great, big, giant, gargantuan reason ...