Referring to the lackadaisical approach of shortstop Roger Dorn from the movie Major League, the phrase is used to show one's lack of desire to initiate the romantic or sexual pursuit of another individual while simultaneously indicating that one would still be receptive if said individual was to him/herself initiate the pursuit.
"Hey, why don't you go after that one chick? She's kinda cute"
"Meh. She's on The Dorn Rule"
"What do you mean?"
"If it comes at me, I'll catch it. But I'm not going to dive for it."
"Meh. She's on The Dorn Rule"
"What do you mean?"
"If it comes at me, I'll catch it. But I'm not going to dive for it."
by Risky74 February 8, 2009