When the male genitalia is gripped by a hand moving in an octopus-like motion with all five fingers.
This is common practice when the male is not yet erect as it is an effective method of stimulation.
NOTE: Not to be confused with the more portable Squid Grip which is only performed with three fingers (thumb, pointer, middle).
Guy 1: "Yo dawg, have you heard of octopus grip?"
Guy 2: "I was havin' a hard time getting it up so my girl performed that on me last week, niggah!"