As an example of that, let's talk about her whining about John's tragically stupid use of the word "pumpkin" as an endearment. A neutral observer would regard the slang expression as being a rather old-fashioned means of expressing affection; a literal-minded dimwit like Elly would, as I said before, make the absurd mental association "pumpkins are round therefore John is calling me fat" because she needs to believe that she's hideously overweight in order for the world to make sense to her. The idea that she's being paid a genuine compliment is alien to her because she needs to feel bad about life owing to a general feeling that being happy means that she's stupid and silly.
Where her logic fails her is that she's instead known as a pessimistic dumbass who races around hollering about things that she refuses to understand. Idiocy turns to hilarity when we remember that she never figured out why people never ask her advice about anything; I hate to keep repeating that that's because they don't want to listen to a long-winded, angry tantrum that's based on Mom's willful refusal to understand what's at stake but since she's never going to learn, can't avoid doing so.