What's the meaning of this joke? Johnnie: I didn't know where the Azores were...

[Plr0201]

Johnnie: I didn't know where the Azores were.
Pa: Serves you right. Aren't I always saying you'll get into trouble one day for not remembering where you've put things?
Why Pa says"where you've put things"???

[Mister Micawber]

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Papa doesn't know that the Azores are an island group; he ignorantly thinks that the Azores are his son's belongings.
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Native English teacher at Mister Micawber's