The first sign I received was an e-mail from a friend (more of a civilian than a ravening cinephile like yours truly) raving about the “The Hangover.” After a response from me that I’d already written that the picture seemed like a possible sleeper, he mentioned that he saw it with a healthy sized crowd for a relatively early show, but by the time he exited at about 8:30 or so, the theater staff at the Northern California multiplex was announcing the comedy was sold out for the entire night.

Then, going on my morning blog/pub patrol, I found that Nikki Finke and THR (and I’m sure Variety too, but do you really need a third source for the same info?) are abuzz with reports that the modest, R-rated comedy earned a cool $16.5 million yesterday. It defeated not only “Land of the Lost,” which unsurprisingly ran a mediocre-at-best third in the wake of a lot of negative buzz, but far more surprisingly, the beloved (but perhaps a bit family friendly for a Friday night) “Up.” And it did it with a starless cast of actors, who would ordinarily be in supporting roles in a film like this.

Once upon a time, my friends, even the big studios occasionally lowered their financial risk for slightly off-kilter projects by populating them with relative unknowns. Major ensemble-comedy releases like “American Graffitti,” “M*A*S*H,” or “Animal House” could make superstars, rather than simply relying on already huge names to fill every seat on the very first night. Of course, this was back when movies initially opened in a small number of theaters in large cities, with gradually expanding releases that allowed time for word of mouth to spread. The meant that not every film was expected to be as pre-sold as a Big Mac.

It’s still possible that “Up” will stage a comeback with families hitting the screens today and tomorrow, but “The Hangover” is now a verifiable sleeper hit and concerns that the appearance of Mike Tyson might backfire because of his recent extremely sad family tragedy seem to be more or less baseless. (Eternal interest in gossip notwithstanding, maybe the general audience is a bit less emotionally wrapped up in the personal lives of celebrities than you’d think.)

It’s nice to see that, even in today’s truly hostile and originality-killing marketplace, Pixar isn’t the only place where filmmakers make a star-free killing by simply entertaining an audience. (And folks, if you can’t get in to see “The Hangover” tonight, consider another film that’s a bit of a throwback to a less calculating Hollywood, “Drag Me to Hell.”)

UPDATE: I forgot to add that my friend also mentioned something I’d somehow missed — that the early reaction to “The Hangover” was so strong that Warners was already publicly discussing a sequel even before the release of the film. I think it’s safe to say that there are some very happy agents in Hollywood right now. One thing is certain, “The Hangover II” will be more expensive than the first.