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general::
Phrase(s): (Do you) want to know something? [and] (You want to) know something?
an expression used to open a conversation or switch to a new topic. • John: Do you want to know something? Sue: What? John: Your hem is torn. • Bill: Hey, Tom! Know something? Tom: What is it? Bill: It’s really hot today. Tom: Don’t I know it!
McGrawhill's American Idioms And Phrasal Verbs