Where one stabs another with a sharp object (shank). Attacks often centered around obliques (lower front and back sides). Called this because supposedly people watching out for this type of attack would duct tape phonebooks around their abdomen.
Person: "So it was a failed rape?"
Witness: "Hell yea, Mrs. Johnson's 9 year old son came outta nowhere and phone checked his ass with a pencil."
In Cali at least it means to do something with around a dozen other people with an assertive mindset. Often in regards to going to a party or club with liquor and drugs involved. Not necessarily with hostile intentions.