So much of comedy depends on us liking the characters. If we like them, we are much more likely to laugh with them or at them. Bill and Ted's Excellent Adventure is a case in point: it's funny largely because, darn it, they may be dim, but they are endearingly dim, and maybe they actually understand more of the essentials of life than a lot of smarter people do.

The premise of this crazy movie is that Bill and Ted, high school students, need to pass their history class or the world will come to an end. I mean this literally, I think, but I wouldn't dream of explaining. But it's ok, because a mysterious man with a time machine comes to the rescue. This leads to visits to famous persons from a variety of historical eras. Watching them interact with staples of modern society is one of the joys of this film, particularly since a lot of narrative grunt work is avoided by having the characters accept the existence of a time machine and a radically different future without question. Another of the joys of the film is the way it exploits time for humor: scarcely an opportunity is missed to take advantage of a temporal paradox.

Bill and Ted are characters inextricably rooted in their time and generation that they became dated just a few years later. Yet the film's appeal is much broader, not so constrained by time, if you will excuse the wordplay. It is smarter than its characters are. Smarter, but not above them.