This week, it was some expensive glasses. Before that, it was the snow shovel, right after he was asked to shovel the driveway.
Your son agrees to perform a chore or task that he doesn't want to do, but then lashes out in anger by "accidentally" breaking a dish or wrecking the snow shovel.
Examples of common devices that are poorly designed ergonomically include the snow shovel and the computer or typewriter keyboard.