...which I never owned.
I did have a small toy plastic submarine. I don't remember it in its intact state; I only remember it getting broken when Grandma Ethel trod on it on the dining room floor. Accidentally of course. No doubt I got a curt rebuke along from Mum along the lines of 'Well, you shouldn't leave your toys lying around'.
I wanted another submarine all the same, of course, and there was a nice yellow one from the Beatles film in the window of Johnson's.
Mum said she would buy me the Yellow Submarine if I managed to go a certain amount of time without wetting the bed. I never did get it, though I feel sure I must have passed the required timespan by now.
I'm tempted to give her a call immediately and remind her of the deal, since there's one of those very submarines on Ebay with an asking price of £35, and only 25 minutes of the auction left to go, but it's now 12.15am and she'll be asleep so I'd better let it go. Shame.