Of course it started with a bet.
Min (short for Minerva) has just been dumped by her boyfriend David, who she wasn't even sure she liked very much, three weeks before her sister's wedding. Min is an actuary, and on the chubby side, so she's pretty sure she'll have to listen to her mother's recriminations when she shows up to the wedding dateless. When she overhears David the ex, make a bet that his friend Cal can't get Min into bed, Min decides maybe she can get some revenge, and a hot (if worthless) date to the wedding in one swoop.
Cal hardly ever turns away from a bet, but he's actually not sleazy enough to bet on getting a woman into bed. What he does bet on, is that he can get her to leave the bar with him. He figures he's at least that charming. But since Min is onto him, he actually won't get very far with his legendary charm.
Through a series of extremely odd coincidences, and maybe a little fate, and despite their psychotic exes, Min and Cal keep finding themselves together. Jennifer Crusie actually does a really good job of making you see why a guy like Cal might fall for a girl like Min. And he even talks her out of her perpetual dieting. (But seriously ladies, diet if you want to, but nobody and I mean nobody, wants to hear you whine about all the things you choose to deny yourself.) This was a funny and frothy good book.