What commercial is so annoying it makes you want to boycott the product they're selling?

Well, the ad is like 40 years old now but McDonald's used to have this ad for some "McDLT, people are dancing and singing around about some d4mn hamburger. The second-hand embarrassment is almost lethal. The one with Jason Alexander (who I cannot stand)

I guess it is not relevant today but it is the WORST ad I have ever seen in my life. Watch at your own risk.