In a paper published in this month's issue of the journal Evolutionary Psychology, Kruger interviewed 475 college students and found that 27 percent of the men and 14 percent of the women reported trying to trade something to get sex. "Sometimes it was money, sometimes it was funding voice lessons, and sometimes it was giving tickets to the Ohio State versus Michigan game," he said. "There's a black market for those tickets - they're quite sought after."
Conversely, about 5 percent of men and 9 percent of women reported offering sex in the hope of getting some kind of freebie.
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