"The Hammer" is the nickname given to Bubbles' father [1]. He was a hockey player in the local hockey arena near Sunnyvale in the 1960's and 1970's. According to Bubbles, "The Hammer" got his nickname from his habit of getting into fights on the rink as soon as the puck was dropped. He also apparantly drank 40oz of alcohol and was drunk during his games. Bubbles also said he was not a good fighter, but the crowd loved his fights anyway.
Sometime when Bubbles was a child, "The Hammer" got drunk and angered some "very bad" men at a legion. So in July of 1976, he and his wife decided that they had to leave for the safety of themselves and for Bubbles. He arranged for Bubbles to stay at Julian's Grandmother's trailer with Julian and left, never returning to see Bubbles. Bubbles only learned of all of this in Christmas of 1997, and the information was not ever given in the context of the TPB canon, but in the interview conducted in 2011 when he made a classic appearance on 'Hockey Night in Canada'.