Sometimes what seems like an amazing idea within the confines of an agency conference room ends up being a total nightmare in the real world. It really makes the theory of groupthink ring true.

Other times, the idea is solid but the execution fails. Most marketers have at least a few of these in their past, us being human and all, and so far, 2013 has seen its fair share of marketing flops. It's safe to say we can all learn from these five examples.

1. LG SOUTH KOREA'S “WORLD WAR G” INCIDENT  

Most marketing flops just fail to draw the right kind of attention. LG South Korea’s promotion for the G2 smartphone took it a step further and ended up with 20 consumers injured.

The stunt, in Seoul, seemed harmless enough at first. The tech company had 100 helium balloons it planned to release in an outdoor park in the city. Each of the balloons was attached to a voucher for a free LG G2 smartphone (valued at about $851).

Things went south when a large crowd showed up carrying BB guns and other weapons – one attendee was spotting holding a pointed staff. LG hadn't anticipated such a large or aggressive crowd and couldn't control the swarm with the security hired for the event.

A public apology soon followed, as did the cancellation of all other promotional events LG had scheduled in South Korea.

2. HYUNDAI MAKES LIGHT OF SUICIDE 

There are certain subjects advertising should never attempt to make light of. In an attempt to make a viral video, Hyundai created a spot that depicted a man attempting to commit suicide by redirecting exhaust into the cabin of his Hyundai ix35. The man is ultimately unsuccessful because of the car’s clean emissions and sulks back into his home.

The video ad immediately provoked backlash from marketers and consumers, who said that it was in bad taste. Most famously, marketing executive Holly Brockwell wrote an open letter to the brand that included a suicide note from her father, who killed himself in the manner depicted.

Hyundai quickly pulled the ad, which only aired in Europe, but pulled another bad move when it tried to pass the blame. The automaker said it wasn't involved with the ad directly and that Innocean Europe was responsible—which is true, but both are owned by the same parent company.

3. CHIPOTLE AND THE SCARECROW 

Chipotle's recent "Scarecrow" spot did a lot of things right. It was created by talented designers, used music by Fiona Apple to great effect and portrayed a positive social message. The video quickly went viral, certainly one of the goals in creating it.

The trouble lies within the social message the ad is sending. The scarecrow in the video works for a factory food producer, and throughout the video, you see different examples of the sad realities of factory farming. In the end, the scarecrow is inspired to begin growing his own food and starts an organic food stand.

While the ad succeeded in drawing attention with well over 6 million views on YouTube, it falls short in its message of "Don’t eat mass-produced food from a mass-produced food chain." As The Washington Post's Alexandra Petri wrote, one of her friends responded to the commercial with, “That doesn’t make me want to eat Chipotle. That makes me want to curl up in a vegan coma and never eat again.” 

4. AT&T’s 9/11 SMARTPHONE TWEET 

Every year on September 11, there are a barrage of brands showing their respect on social media. Some are tasteful and pass along barely noticed, but this year, AT&T ruffled some feathers.

The mobile provider's tweet featured a photo of the current New York City skyline, a hand in the foreground holding up an AT&T phone with the Tribute in Light memorial captured on the screen. Immediately, a backlash of negative tweets began rolling in. Basically, Twitter users saw it as a shameless attempt to promote the company's smartphones using a national tragedy. The tweet was only up for one hour before AT&T deleted it and issued an apology.

5) NESQUIK'S "NATIONAL BUNNY EARS DAY"

Unlike other campaigns on this list, there is nothing inherently offensive about Nesquik’s "National Bunny Ears Day" campaign. The real reason it was one of the biggest marketing flops of 2013 is because nobody seemed to care.

For the campaign, Nesquik developed a “bunny-fier” mobile app that automatically added bunny ears to people in photos. The brand hoped to promote the app by declaring a "National Bunny Ears Day" on Sept. 16, encouraging app users to share their photos on Twitter and Instagram with the hashtag #nationalbunnyearsday.

While a cute idea, it never took off—even with celebrity chef Giada De Laurentiis using the hashtag. In the end, the hashtag only received nine mentions on Twitter and two on Instagram. The idea just didn’t hold much interest and wasn’t tied to a bigger announcement or event.