There is a Steam Community user by the name of "Shaxx". (http://steamcommunity.com/id/Shax-Leone/) One of his other friends started saying to him "Shaxx is love Shaxx is life." Later the friend started calling him "Mighty Ogrelord Shaxx." One day, the friend was in a Steam group chat with Shaxx. In the chat, his friend made a parody of "Shrek is love Shrek is life" but with Shaxx instead of Shrek. So after that, his friend started calling Shaxx "Shrek" as a nickname. Then later on other people of the Steam community followed the meme and started calling him Shrek. The song "Smash Mouth All-Star" is nicknamed "Shaxx's theme song" on the Steam community.