Ever since Greg's youtube channel gained popularity, people misread his username as onion. Even today fans suffer from auto-correcting his name to onion.
To spite Greg and his known hatred for mispronunciation of his username Onision, anti-onision vloggers and later bloggers started calling him onion.
In 2013, Greg started using the term Onion on social media to show haters he wasn't bothered by there nickname. He began stating that "Smurfs call me "Onion" because i make them cry." on his facebook. Greg continues to use variations of this phrase today.