Angry Birds

Angry Birds postage stamps; Source: Posti
Finland’s Posti (Itella Posti Oy) issued the world’s first official Angry Birds stamps on 9 September 2013, featuring six of the popular game characters – five birds and one pig. The stamps were designed by Toni Kysenius, Art Director at Rovio Entertainment, who also designed the HockeyBird character and related stamp issue for last year’s IIHF Ice Hockey World Championships.
In order to prevent counterfeiting/ensure authenticity, the Angry Birds stamps feature a pattern which is only visible under UV light. In addition, an irregular perforation follows the shape of the characters. The sheet of six 1st class stamps also includes Priority labels fitting the appearance of the stamps.
The concept of the Angry Birds game is not new. It’s like Crush the Castle. It’s popularity though is brought about by a smooth interface, very marketable/memorable elements to a genre that was already fun, and it being one of the earliest iPhone/Android games with such a solid engine. Since 2009, the globally successful franchise is now a worldwide phenomenon:
There has been 11 Angry Birds-related games (including spin-offs).
There is an Angry Birds land at the Särkänniemi adventure park in Tampere, Finland that opened in April 2012.
There’s even a 3D animated movie scheduled for summer 2016 (Source).
Some trivia: The reason the enemies in the game Angry Birds are pigs is because the swine flu epidemic was going around at the time of the game’s development. That would also explain why the pigs are green (Source).
Anyway, here’s a real life angry bird (they exist!):

This guy is not amused. Source: Imgur
References:
https://verkkokauppa.posti.fi/PublishedService?pageID=9&itemcode=108159
http://www.pocketgamer.co.uk/r/Multiformat/Angry+Birds/news.asp?c=24243
http://www.whiteboardmag.com/confirmed-angry-birds-movie-hits-box-office-in-2016/