The Waterboy simply follows the Sandler system of making money off of slapstick and also the fact that some people are not very smart (but in this case extremely strong.)

His name is Bobby Boucher (played by Sandler) and he is a simpleton that just happens to have an extreme love of very clean water. He doesn't have any talents as far as he knows and he isn't particularly smart. A lot of this can be attributed to his overbearing, extremely conservative mother Helen (Kathy Bates.)

she really hates the fooseball

One day while working as, you guessed it, the waterboy, it is discovered that he hits like a freight train on a football field and is recruited to play for a team that has lost 40 straight games and Bobby, not surprisingly, single handedly turns the entire team around and gains national attention for this team that was otherwise never paid attention to.

This really isn't all that different from everything else Sandler does / produces. For whatever reason Adam's combination of slapstick and still man-child comedy just makes me and millions of other people laugh. This movie made more than 100 million dollars despite the fact that it has almost no production value whatsoever. You have to admire this.

I have a very profound appreciation for Adam Sandler because he is able to make people laugh with something so incredibly stupid that you kind of feel a little bit bad about being amused by it later. It isn't just me, it isn't just USA, it is the entire world. This is why Sandler makes critically panned movies over and over and over and yet these movies make tens if not hundreds of millions of dollars.