Sometimes the hardest thing to do is to get your story going. And I get it, if you know all the fun and games you want to have with your premise, it can be tedious to line up the dominoes to get to that result in a plausible way. So the lazy screenwriter opts to artificially motivate some implausible behavior with that tried and true method - the bet.
The terms could be anything from the hero having six weeks to turn a outcast girl into the prom queen (She's All That, brilliantly parodied in Not Another Teen Movie) or a ridiculously convoluted story where the male bets that he can get any girl to fall in love with him in ten days, only to be set up with a woman tasked with alienating a guy within ten days (How To Lose a Guy in Ten Days). It almost always feels contrived and artificial. If you find yourself using a bet to get the action going, please give serious thought to any other way to get your characters to interact.
One of the big problems I have with this is that it not only makes the set-up contrived, but in romantic comedies involving bets, it all but ensures that the turning point at the end of Act Two will find the object of the bet finding out about the terms of the wager. Thus, they'll feel used and lash out at the person who was using them. However, this won't happen until just after the film's protagonist has expressed either misgivings about collecting on the bet, or has affirmed that the experience has caused them to develop genuine feelings for the other person. Thus, even though the whole relationship is built on a lie, genuine feelings have resulted, thus creating emotional stakes for the protagonist when the other character predictably says "I never want to see you again."
Then the third act becomes all about the protagonist winning back their former mark, usually by appealing to some emotional tie that was established during a bonding moment between the two midway through the story.
I'm sure there's an argument to be made that such premises are high concept and easy to promote, but I feel the predictability of such a story is likely to work against the script. If by page ten I can already guess exactly where the story is going to go, it's going to be a boring read. Never forget the First Commandment of Screenwriting - "Thou shalt not bore the reader."