This extension is deprecated: it was written for Opera 12, it will not work (I guess?) on Opera >= 15.
Old README contents
Meme Smileys is a silly Opera extension (docs) that displays meme-style smileys on social networking sites (as of this writing, Facebook and Twitter). The official, released version is always availabe at the Opera extensions website.
I basically thought Troll-emoticons for Facebook & Twitter, a Google Chrome extension, was funny, and implemented an Opera extension inspired by it.