Another campaign that would light up the culture, "Whassup?" featured Charles Stone III and his buddies groaning and bellowing the catchphrase at each other over and over. Simple, infectious, and hilarious, it originated as a short film before DDB got Stone and friends to remake it as a commercial. Before long, it seemed everyone in America, Budweiser drinkers or not, was parroting the phrase, while Stone was picking up multiple ad awards.
Full list: The 10 Funniest Commercials of All Time.