Mook is a hippie friend of Helen and Jake in C.E. Forman's The Lost Seasons series, making his only appearance in "Fireworks." Constantly high on a strong substance, Mook doesn't converse so much as speak in song lyrics and mantras of the day. His "gang" considers him their resident philosopher, though most of the time, they aren't sure what he's saying. Jake talked to him about his feelings for Helen and Mook seemed to be sympathetic.
In 1968/9, he was part of the group that took over the dean's office in a successful protest against Middleton College's segregationist policies. During a vist to Boulder in 1969, he was assaulted by a police officer and then arrested.
It is unclear how Mook managed to graduate from college, unless one assumes that Middleton's standards were dropping even then.
Forman developed Mook and the other characters after viewing clips from "That Was Then, This Is Dumb."