Mine was a Game & Watch:
Helmet.
Given to me in Christmas 1980 or 81 by my neighbours who had just picked it up in Hong Kong. I played it so much that Christmas day that my mum took the batteries out. I screamed. Hard.
When the batteries were put back in, the clock blinked 12:00, you see. It was BROKEN!! I screamed some more. Mum had to go next door and ask the neighbours to set the clock for me so I would stop screaming.
Mum and I were just talking about that the other day. Funny sh1t.