BT Pes 74a(12) :אידי דאית ביה שיבי מהנפיק מיא והוה ליה מבושל‏ : since it [i.e. a spit made of a palm branch] has grooves, it exudes water (into the meat) and it has achieved a boiled state
See the entire entry for šyb n.m. chip, groove (??)