Arnold Schwarzenegger's Son Joseph Baena -- The Boy Who Would Be King

Arnold Schwarzenegger's love child, Joseph Baena, looked like a king during his high school's homecoming event ... just not a homecoming king.

Baena got his tux swag on ... and made a run for the crown at Frontier High School in Bakersfield, CA last month. He made it to the top 5, but lost the ultimate title to some other kid ... whose father is not ex-governor or a Hollywood superstar.

Sometimes life is unfair -- but Joe already knew that.