The Happy Onion is a health item in the game that is designed to completely restore Jack's health.
- Howard: "Is that an onion in your pocket, or you're just happy to see me?"
Kreese: "I know you're trying to do an Happy Onion joke, but it's not working."
Howard: "I..know. But I'm trying..."
Kreese: "...Stop trying!!"
- Kreese: "Jack looks better after the Happy Onion."
Howard: " I always feel better after the Happy Ending!"
Kreese: "Not Happy Ending, you idiot, Happy Onion!"
Howard: "Obviously, you've never fucked an onion!"
- Jack can be seen eating a happy onion in a cut scene during the Mad Castle arc.
- The happy onion is the only non-weapon item that has to be unlocked from a weapons case in order to be accessed on lower levels (It is shown centered at in the tower elevator on the last level as an exception).
- Happy onions are supplied by external sources in lower levels, where non-unlocked sequences apply.
- In the tower colosseum on the last level, a Geishas supply Jack with happy onions at the last second prior to death (When his health is near 1 HP [One hit and he's down]).
- According to commentator quotes, Howard has had sex with an onion.