I Don't Think That's Such a Good Idea

I forgot to include a character that says "Uh, I don't think that's such a good idea", at every juncture.

—Tom Siddell on Gunnerkrigg Court

In many media, especially in children's shows, there is a character who is passive to the point of being annoying. While everyone else is wanting to go off and try a dangerous adventure, they think that maybe everybody would be better off if they just stayed put or went bowling.

This is what the character says as a weak argument against the adventure. Usually the character is blown off as being stupid, unfun, out-of-touch, and uptight. But the overall portrayal is based on whether the adventure is seen as a good thing or a bad thing. If it's the wimpy character in a group of good guys, it's bad. But if we're trying to teach an Aesop, then we were supposed to be listening to the wimpy guy.

Usually the Straight Man does this in in comedies. The wacky guy wants to do something stupid, the Straight Man cautions against it, Mr. Wacky does it anyway, and Hilarity Ensues. Straight Man rolls his eyes and laments, What an Idiot!! At least for the moment.

Compare The Drag Along, The Complainer Is Always Wrong.

Examples of I Don't Think That's Such a Good Idea include:

Film

Aliens:

Frost: Man, I'm telling you, I got a bad feeling about this drop.
Crowe: You always say that, Frost. You always say, "I got a bad feeling about this drop."

C-3PO from Star Wars.

Artoo--I'm not sure that's such a good idea. It's a very long drooooooppp!
Surrender is a perfectly viable alternative! The Empire may be gracious enough to-- *click*

Live Action Television

One episode of Mystery Science Theater 3000 made fun of the use of this trope on Baywatch:

Mike (or was it Joel?): Now, don't you kids go swimming off the pier! It's dangerous! Five minutes later...
Robots: Ah! Help! We're drowning off the pier! Heeelp!

Dads Army's Sgt. Wilson has something very similar as his Catch Phrase, in response to The Neidermeyer's Zany Scheme of the week.

Do you think that's wise, sir?

My Name Is Earl:

Randy: Earl, I need you to go to Joy's and punch her in the face.
Earl: I don't think that's such a good idea Randy.
Randy: Are you saying that because it's a great idea?

Kel of Kenan and Kel usually thinks this about Kenan's ideas. Kel's often right.

Newspaper Comics

Hobbes from Calvin and Hobbes is known for being this way around Calvin, only reluctantly going along with his crazy ideas related to the Cardboard Box (the time travel scenes in particular), and stepping off at the last moment before their toboggan careens down into the abyss.

Calvin: C'mon, what could go wrong?
Hobbes: Whenever you ask me that, my tail goes all fuzzy.
Calvin: Oh, knock it off.

Tabletop Games

A well-known rule of thumb in Role-Playing Games: "When the GM asks you 'are you sure?', that is a warning sign."

Western Animation

In Rugrats, Chuckie used this exact phrase so often that it became a Catch Phrase. Even though his objections are almost always ignored, the It's a Wonderful Plot episode, showed the world turned into a wasteland torn apart by babies.

Chuckie: Why are all the babies causing so much trouble?
Guardian Angel: I guess there's no one around to tell them it's not such a good idea!

The Wonder Twins shorts on Superfriends used this as a matter of formula. One teenager would suggest doing something really stupid. Another one would say it's not a good idea. The first one blows the second one off. When the first one gets in big trouble, the second one ends up calling the Wonder Twins.
In The Simpsons, Marge Simpson does this with Homer's ill-judged ideas, to the point where they started lampshading it. She's usually right.
Boo-Boo reacts to Yogi Bear's zany schemes with his Catch Phrase, "The ranger's not gonna like it, Yogi."
In South Park episodes, "Pandemic" and "Pandemic 2: The Startling", Craig turns into this guy, but more to the effect of lampshading the whole show.
- An older episode does something similar—Barbara Streisand is trying to get Cartman's ancient mystical artifact, and she persuades the kids to go for a ride in her car. Kyle briefly realizes that they're not supposed to go into cars with strangers, but Cartman curtly replies by saying "not if they're giving you money dumbass!" Subverted in that, of course, getting into the car with Barbara Streisand was a really dumb thing to do.
Arnold in The Magic School Bus.
In a season one episode of Ed, Edd 'n' Eddy:

Edd: Eddy, I don't think this is such a good idea!
Eddy: Have I ever steered you wrong?
Edd: Yes.

Zilly on Dastardly and Muttley in Their Flying Machines. Invokes this with every invention Klunk comes up with.