Surrounded by Smart People

Bob has just been invited to attend the Elaborate University High for the Gifted. He himself is only a normal guy, but his common sense with an experiment involving mutant beavers running amok in his hometown caught the attention of the prep school. Bob now finds that his roommate is a ninth-degree black belt and can build a nuclear reactor with a paper clip and a rubber band. The classes here cover nanotechnology and xenobiology, and physical education involves math problems in Ancient Egyptian. Bob now has to deal with all this weirdness and may or may not have to fix whatever this group of geniuses throw at him.

Bob is now Surrounded by Smart People.

While the Only Sane Man is usually Surrounded by Idiots, this guy is an Every Man who finds himself in a group or place filled with people smarter and/or more skilled than he is. The Only Sane Man usually has to deal with the fallout of all that smartness in one place, often being the voice of reason in the group. This person may have a military or police-based background, serving as the Badass among the smart folk.

Examples of Surrounded by Smart People include:

Anime and Manga

In Haruhi Suzumiya, Kyon is the only non-superpowered member of the S.O.S. Brigade and many of the events they get caught up in tend to be over his head. As such, he often has to rely on Yuki's Techno Babble explanations, or Koizumi whenever he can't understand Yuki, to get a handle on things. Mikuru also chips in, as much as regulation will allow, since most of what she knows is "classified".
Zenkichi from Medaka Box. While the people around him are certainly quirky, their abilities can't really be denied. Akune and Kikaijima are both scholarship students and specials, Medaka herself is talented at everything as an abnormal. Not to mention the Class 13, who are all incredibly talented in one area (though at a price). He is able to keep up with them with his abnormal amount of determination.

Fan Works

Xander Harris invokes the trope as the reason for his academic improvement after his first year at Hogwarts in the Buffy the Vampire Slayer/Harry Potter/The Addams Family Mega Crossover Alexander Harris and the Shadow Council, by "Tenhawk": “Find the smartest girls in school and hang around them.”

Live-Action TV

In the Syfy show Eureka, Sheriff Carter often has to deal with the weirdness caused by the geniuses living in the town. The sheriff himself is a former U.S marshal.
In Knight Rider, Michael Knight is friends with an educated British man, a Wrench Wench and an artificially intelligent car.
- This also occurs in the 2008 Knight Rider series, where the main character is surrounded by an AI expert, a woman who can speak six languages, a computer whiz and a Deadpan Snarker Ford Mustang.
The whole concept behind Head of the Class.
Penny in The Big Bang Theory qualifies, being the only non-science geek in the group. That's pretty much the entire basis for her character, really

Web Comics

In Girl Genius, Herr Zinzer is surrounded by incredibly intelligent "sparks" who can dream up wonders of science before breakfast. However, when an experiment goes horribly awry, he's the only one clever enough to simply pull the plug instead of panicking and shouting, "Nothing can stop it now!!!"

Western Animation

In the first regular episode of The Simpsons, "Bart the Genius", Bart is mistaken for a genius after he cheats on a test and is enrolled in a school for prodigies.