He tries to turn on the light, the bulb is dead, unscrews it, then as he's getting the bulb the shelf in the cabinet it's in is loose.
He gets a screwdriver to fix the cabinet, but the rails on the drawer the screwdriver's in are squeaky. He gets some WD-40 to fix that, but the can of WD-40 is empty. He then gets in the car, which refuses to start.
Then his wife gets home, and he's underneath the car covered in motor oil. "Hal, did you replace that light bulb in the kitchen?" "WHAT DOES IT LOOK LIKE I'M DOING?!".
It’s the genuine exasperation and haste that sells it. He hasn’t forgotten what he originally started. But he’s earnestly doing his best while seemingly everything fails needing urgent attention.
And he missed the obvious (with hindsight) options of, calling a taxi, catching a bus, etc.
This is going to sound like nitpicking, but no, and the distinction is what makes it a good example of ADHD. "Yak shaving" (at least as I've always heard it used) isn't applicable here.
It would be if she came home and he's repairing his circular saw or something. Why is he doing that? It's because the ladder's broken, and you need the ladder to reach the light bulb, and to fix the ladder you need the saw.
So, a seemingly unrelated task that an outsider observing you might be surprised that you're engaged in, but which is required to allow you to solve the problem at hand. That's "Yak shaving".
Whereas he doesn't actually need to fix the shelf, or lubricate the drawer, or fix the car.
The only thing that would make it better is if he'd somehow managed to misplace the lightbulbs along the way, with Lois's looking annoyed over a forced candlelight dinner.
Fair point, I missed the distinction between simple distractions and having to take care of an ever-growing chain reaction of necessary tasks to fulfil the original mission.
He tries to turn on the light, the bulb is dead, unscrews it, then as he's getting the bulb the shelf in the cabinet it's in is loose.
He gets a screwdriver to fix the cabinet, but the rails on the drawer the screwdriver's in are squeaky. He gets some WD-40 to fix that, but the can of WD-40 is empty. He then gets in the car, which refuses to start.
Then his wife gets home, and he's underneath the car covered in motor oil. "Hal, did you replace that light bulb in the kitchen?" "WHAT DOES IT LOOK LIKE I'M DOING?!".