Masochist (3.5e Flaw)
From D&D Wiki
You are incapable of spending a day without having pain inflicted upon you from another creature.
Effect: At least once per day, typically upon waking or beginning a journey (Essentially once per session), you must inflict at least 1d4 damage or 1d8 of non-lethal damage to yourself. If undone, you suffer a -4 on constitution and fortitude saves for the entire day. A party member cannot inflict this pain for you.