The De Beers diamond campaign. It's been absolutely historical, shaped/faked the entire diamond market and made diamond engagement rings part of our culture. If you read into it it's pretty damn interesting.
As far as just funny so I enjoy it though, probably that Staples commercial with the dad dancing up and down the school supply aisle with a shopping cart to "it's the most wonderful time of the year" and the two children trudging behind him.
Apparently the little boy in the costume had never seen Star Wars until he did the commercial. He also has a heart issue. (I remember like the day after this commercial aired he was on some show being interviewed. I think he has a heart monitor or something.)
I don't think I actually saw it on TV but I think it's adorable.