IT MUST BE AWESOME being friends with Adam Sandler, because he will gladly build an entire movie around the premise of hanging out with you. It's a lackadaisical approach to filmmaking that's repeatedly proven its bankability: From Billy Madison to Grown Ups, Sandler has built an empire on sweet, stupid movies that ask nothing more from their stars or audience than to hang out for a while.
In Just Go with It, the people hanging out are Sandler, Jennifer Aniston, and Sandler Pal No. 2, Nick Swardson. (Sandler Pal No. 1 will always be Rob Schneider. Sorry, Swardson!) The places they are hanging out are LA and Hawaii, because one is in their backyard, and the other is Hawaii. Filling out the cast is the usual collection of precocious kids and colorful grotesques that populate every other Happy Madison production.
In fact, if it weren't for the plot, Just Go with It would basically just be an expensive vacation video for rich people—which wouldn't be that bad, as Sandler and Aniston both effectively play themselves, have a winning chemistry, and are fun to watch. But alas, there has to be a plot and, alas, like in every Happy Madison movie, that plot is needlessly convoluted: Sandler is a plastic surgeon, y'see, but he's afraid of commitment, so he habitually pretends he's already married. After meeting a young sixth-grade teacher with a heart of gold (played, collectively, by Brooklyn Decker's tits and ass), Sandler explains away his fake wedding ring by constructing a lie in which his assistant (Aniston) pretends she's his ex-wife, while her kids pretend he's their dad.
Lies beget bigger lies, people get married, Nicole Kidman shows up, Dave Matthews makes a surprise appearance where he picks a coconut up off the floor with his ass, and everyone gets what they want: Sandler makes another movie where he plays himself sitting by the beach, Aniston shows off her still-toned body in a bikini, Swardson makes enough money to eat, and the audience spends another hour and a half imagining how awesome it would be to be Adam Sandler's friend.