"Gatering" someone is defined by looking in the eyes with a smile on your face while missing a minimum of 85% of your teeth. Also, in order "to gater" someone you have to have at least one major handicap or abnormal genetic disfunction - such as having a third eye. Gatering someone online describes the constant spam and annoyance, usually via manga or anime related internet links and memes, of a friend.
He just gatered me sending a gif of a cute looking japanese girl from an anime. He then asked me on voice chat, although I couldn't understand him because of his mumbling (due to lack of teeth), wether or not I would like to watch an anime with him. I hate him when he is gatering.