where do i get the quest for cannibal johnson

He's part of Arcade Gannon's personal quest, Auld Lang Syne.

i have arcade gannon as my follower and i havent gotten a quest from him

Like most (if not all) companion quests, there are certain triggers that you must activate prior to him giving you the quest.

If these triggers are not activated then he will not give you the quest

The triggers are posted on wiki