Ambush Marketing
Using the awareness and image of another brand or event is sometimes called ambush marketing.
Very large brands use ambush marketing. The most prominent examples are brands associating themselves to an event for which they are not sponsors. Many brands for example communicate around the football theme during the worldcup even if they are not sponsors. Ambush marketing becomes illegal when it infringes on other brands' intellectual property. The legal situation is often unclear which results in disputes.
Examples:
Pepsi associating itself to soccer and the worldcup. Official sponsor coca-cola
Linford Christie wears contact lenses with Puma logo during a press conference during the Atlanta Olympics: Reebok was sponsor of the event.
Kinesio tapes offered 15,000 rolls of its tapes to athletes during the beijing olympics.
