What Is Going On?

When a character enters an episode midway through the story, typically, the first thing they say is, "What is going on?" or "Would someone mind telling me what's going on?" or some other variation on this phrase.

Then the other characters typically give a quick summary of the story so far, or there is a quick cut away to another scene for a bit or simply quick fade in/fade out back to the characters that implies they had just finished giving a detailed briefing of the situation.

The polar opposite is Let Me Get This Straight....

Film
"Westley: Who are you? Are we enemies? Why am I on this wall? Where is Buttercup? Inigo: Let me 'splain. (Beat) No, there is too much. Let me sum up."
 * The Princess Bride, after Westley is revived from being Only Mostly Dead:

"Taggert: What in the wide, wide world o' sports is a-goin' on here?!"
 * Blazing Saddles, when Taggert arrives at the railroad worksite to find all his foremen singing "Camptown Ladies":


 * In Mary Poppins, Mary, Bert, the two children, some other chimney sweeps and Mrs. Banks' suffragette society are dancing through Mr. Banks' house when he comes in. His reaction is to yell "What's all this?" which becomes a part of the song.

Live Action TV

 * Done so often by Mr. Belding on Saved by the Bell that "Hey hey hey, what is going on here?" became his Catch Phrase (and is worth two sips in the Drinking Game).
 * Given the incredibly serial nature of 24, this trope pops up a lot, mostly after Jack or CTU has uncovered a new threat, the President asks to be "brought up to speed".
 * This happens so often, in fact, that certain characters (Tim Woods, amongst others) were seemingly created for the sole purpose of filling the audience - and the President - in on the details of what just happened.
 * Parodied in the first season finale of Drawn Together, where Xandir would shout this catch-phrase out whenever the narrator introduced a Shocking Swerve to the contest, which seemed to happen once every five minutes.
 * Because said bit is viewed from outside the house to hide the exact emotion of the one yelling the phrase, it might have been a spoof of promos (which were, at the time, being played on the network constantly) for Spike TV's The Joe Schmo Show, a fake reality show that one contestant is led to believe is real. The show is also alluded to later in the same episode.
 * General Hammond from Stargate SG-1 often will enter a strange scene with "What is going on here?!" (sometimes with "the hell" thrown in), or occasionally "What the hell are you/do you think you're doing?!"

Web Comics

 * El Goonish Shive Parodies this trope (and lampshades its own predilection towards it) here.