It was a Bud Light ad campaign that originally ran for three years everywhere that Anheuser Busch ran ads. Wikipedia claims it started on Monday Night Football, not the Super Bowl: https://en.wikipedia.org/wiki/Whassup%3F. But in any case, that is hardly the only time it ever ran.
Asking why it became popular may as well be asked of any pop cultural phenomenon that ever becomes popular. 20 people will give 40 opinions. Nobody really knows.
Yep, in the UK we knew it from the Budweiser adverts. Before that there was the frogs Bud, Weis, Er. Apparently they were originally a Superbowl ad, but again they were just shown on normal TV here.