Wally and Beaver make a mess in the garage working on a project that they quickly abandon, and Ward can't get his car in the garage that night when he comes home. When the mess is still there the next night, Ward blows his top and calls the situation stupid.
The next day is Saturday, and Ward has to work that day, but rides with Fred Rutherford, so his car is still in the driveway. Wally and Beaver do clean up the mess that they made, but one of the boards with nails in it has caused the car to have a flat tire. The boys remove the tire, get the flat fixed, and put the tire back on. When Ward calls them on this when he returns he asks them why they felt they had to hide matters. Wally replies that it boiled down to not wanting to be called stupid again by their dad.
The issue is how harsh words can hurt so much more than even blows can, especially from parents. I guess that's especially true when the harsh words are rare, as they were in Ward's case. Eddie, from his anecdotes about his relationship with his parents, has apparently become numb to his father's harsh words. But then see the impact that has had on Eddie's personality!