Walk up to a girl, stare into her eyes, give a soft smile, and say
“He’s a lucky man.”
She replies, “Who?”
“That boyfriend of yours.” you say.
Then you start walking away, waiting for a response.
If no response, you just walk away looking cool, either they respond cause they want to talk, or they dont because they dont want to or they actually have a boyfriend.
If they do respond, reply as follows.
“I dont have a boyfriend”
“Then how about I be your boyfriend?” or
“Then how about you go out with me?”
“Be my boyfriend? I don’t even know your name.”
“Andrew. Nice to meet you. =)”
Essentially, this limits rejection, provides a way out at all times, and leaves the woman to spur the conversation, provided she desires to.