Brolly for Nothing?

A Tit for a Tat (128)

Tit: When I don’t bring my brolly, it rains; when I do, it doesn’t! I brought my brolly for nothing again!
Tat: Isn’t that what you want?
Tit: Bring my brolly for nothing?
Tat: No, that it doesn’t rain.
Tit: Yes. So?
Tat: If you believe bringing your brolly prevents rain, you didn’t bring it for nothing then!

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