Ambush marketing consists in directly interfering with a popular event which benefits of high media exposure without being an official partner or sponsor. The goal is to get visibility for a brand or product without paying for an official partnership.
The most elementary form of ambush marketing is probably the naked "striker" who crosses sports fields during a TV retransmission with the domain name of an online casino tattooed on his chest.
However, ambush marketing operations can be much more planned, organized and be more rewarding for the brand. Aerial marketing in the area of a big event can be considered as ambush marketing.
Instructions are given to TV production teams not to broadcast any ambush marketing operations but those operations can still find a significant echo on the Internet and social networks.
Ambush marketing generally suggests a surprise or a field "attack" during the event which breaks the organizer’s rules. Smoother forms of ambush marketing can be used by simply using the context of the event. In this case it is more appropriate to speak about parasitic marketing or indirect ambush marketing.
During the 2007 Rugby World Cup, french lingerie brand Dim had cheerleaders dressed in lingerie at the Stade de France which attracted the TV cameras and spectator smartphones. Il was clearly an ambush marketing example:
When the same cheerleader team hijack the famous All Blacks Haka, it becomes more an opportunistic or parasitic campaign:
A famous example of ambush marketing for a beer brand during the Soccer World Cup:
An interesting slideshow about ambush marketing: