Justin Bieber's hijinks are apparently contagious ... a woman who claims she was hired to work as his chef has been charged with beating up her boyfriend.
Sara Horowitz -- who placed 4th in Season 2 of "Hell's Kitchen" -- apparently isn't very nimble when it comes to food -- because according to legal docs ... she dropped a cooler filled with food inside a car and it made a mess.
Apparently Sara's boyfriend -- El Paso TV weatherman Mark Mathis -- was none too pleased, and they started arguing. According to cops, things escalated and Sara allegedly punched and kicked Mark, breaking his glasses and scratching his face.
She was arrested April 10 for assault/family violence and charged the next day with a misdemeanor.
We reached out to Sara -- so far, no comment.
Hey Sara ... Justin's available.