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An expression used to hint that a certain idea is obsolete and anyone in their right mind would retire it immediately.
Person 1: I heard all gays are pedophiles too.
Person 2: I don't think anyone's believed that since the 60's.
Person 1: Really?
Person 2: Yeah. I think grandma's gone to bed on that one.
by helyllefilten July 14, 2016
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