to deviate or wander away from the main topic or purpose in speaking or writing; depart from the principal line of argument, plot, study, etc. in order to speak about Kids of Degrass Street, Degrassi Junior High or Degrassi High.
That happened to L.D. in Degrassi High. Then Lucy started to make video tapes for her to cheer her up in hospital. One of them had a rap in it. It was hilarious. But I degrass, what were you saying about your son?