The global rise of social media over the last few years is seeing London 2012 billed as the first truly digital Olympics, presenting unprecedented opportunities for intentional and accidental ambush marketing to “go viral”.

Ambush marketing is an emotionally-charged phrase that refers to the practice of appearing to align a brand with an event for which that brand has not paid for the right to be a sponsor. Probably this practice had existed in some form long before 1984, but the sheer volume of money involved and the worldwide attention given Olympic events have led many to view the 1984 Olympic Games as the origin of ambush marketing.

At the 2012 London games, The International Olympic Committee (IOC) forbids athletes from taking part in advertising for anyone except the 11 international companies that pay around $100 million each for four years of global rights to sponsor the Olympics.

The rules are designed to prevent “ambush marketing”, or non-sponsors getting free publicity on the back of the Games.

Officials became suspicious as an increasing number of athletes from Britain, Chinaand other nations, appeared at events sporting Beats by Dr. Dre in their national colors.

US sports goods manufacturer Nike launched a global TV campaign that coincided with the opening ceremony, featuring sports people in places around the world named London. Nike's arch-rival Adidas paid millions to be an official London 2012 global sponsor. Locog, the official Olympic organizing committee, says it can "take a joke," The Guardian reports. But with official sponsorship tipping the scales at a cool £700,000, it’s a pretty expensive one for the real sponsors, like Nike arch-rival Adidas.

On a slightly smaller budget, UK bottle shop Oddbins created an Olympics-themed ad which is quite open about the fact the Games can’t be mentioned by non-sponsors.

But the business has gone even further than this, by actively rewarding customers that use the brands of sponsors’ rivals during the Games.

Some world famous examples of ambush marketing during Olympic and other major events:

• 1984: Kodak sponsors TV broadcasts, despite Fuji being Los Angeles Olympics' official sponsor; Fuji returns favour at Seoul 1988 Games

• 1992: Nike sponsors news conferences with the US basketball team; Michael Jordan accepts the gold medal for basketball and covers up his Reebok logo

• 1994: American Express runs ads claiming Americans do not need "Visas" to travel to Norway for the Winter Olympics

• 2000: Qantas Airlines' slogan "Spirit of Australia" coincidentally sounds like Games slogan "Share the spirit" to chagrin of official sponsor Ansett Air

• 2010: Dutch brewer Bavaria creates publicity stunt with women wearing orange mini-dresses in stadium during South Africa World Cup; Budweiser was authorised beer

Ambush marketing is usually employed at the times of big sporting events, where big corporations’ cash is on the names of the sporting events without paying the requisite fee, which constitutes the crux of “direct ambush advertising”. However, it is not sporting events only which become the mode of deploying ambush marketing.

The latest war was between Hindustan Unilever’s shampoo brand “Dove” and Procter & Gamble’s shampoo brand “Pantene”. P&G launched its intriguing ad campaign for Pantene with the tagline “A mystery shampoo. Eighty percent women say it is better than anything else.” A few days later and before P&G could launch the new Pantene, Hindustan Unilever ambush the campaign by placing an adjacent hoarding with the tagline “There is no mystery. Dove is the No. 1 shampoo.”, thus ambushing Pantene’s campaign.