muggins

/ˈmʌɡɪnz/
noun
  1. A foolish or gullible person, especially one who is easily tricked or taken advantage of.
    • He played us for muggins and walked away with all the money.
    • I felt like a real muggins for believing his story.
    • Don't be such a muggins — that deal is a scam.
  2. Used humorously to refer to oneself when doing something that seems foolish or when one is the victim of a situation.
    • And who got blamed for the mistake? Muggins, of course.
    • While everyone else went home early, muggins was left to clean up.
    • So muggins here had to stay late and finish the report.