Earl put the rock in the boat. He did this because he wanted to be faster than Lester. When Lester realized the rock made a bigger wake in his boat, he decided to wake board becase he could pick up more chicks. This made Earl VERY ANGRY... because he caught no fish & got no chicks (because Lester was wake-boarding around him all the time). At the end of the day, Lester found out the Earl was a transvestite, so everything worked out ok.
I am getting close to the answer right?