The first time Jennifer Hindieh saw Alexander Najman, she wished he would go away. Instead, after bumming a Marlboro off her in September 2011 at Long Island University, he stuck around and tried to strike up a conversation.

“I was lost in thought,” she said. After fishing a cigarette out of the pack and handing it over, she gave him the universal code to get going. “I looked down at my phone. I was thinking, don’t talk to me.”

Ms. Hindieh, then a freshman at the university’s Post campus, in Brookville, N.Y., was annoyed that Mr. Najman, a graduate student at Stony Brook University working part time in Post’s philosophy department, had trouble taking a hint. She didn’t particularly care for his demeanor, either.

“He was doing the kind of stuff guys do to impress you, acting all full of himself,” she said. After a few drags on his cigarette, though, he made her laugh. By the time he stubbed it out and walked away from the outdoor bench where Ms. Hindieh's smoke plumes had led him, she had forgotten her first impression and given him her phone number.