A lot of times, when someone says something stupid or ridiculous, the reply they get is「バカいえ！」, or when someone says something that's obviously a lie, they will be told 「ウソつけ！」. I've also heard 「ふざけろ」 used similarly. I was wondering, why is it that Japanese likes to use positive imperatives at times like these even though the intent is clearly to call someone out on something or get them to stop? What is the actual implied meaning of these phrases?
This was discussed some here in a question about うそおっしゃい. A similar construction happens in English, as in the famous Dirty Harry line, "Go ahead, make my day." The speaker is telling the listener to "do XXX", with the implication that the speaker will respond immediately by beating the listener in some way. The resulting meaning is thus "don't do XXX" -- basically, a positive imperative is used to express a negative imperative.