Which case(s) for you had the greatest twist? (Please, for the love of God, use spoiler tags if discussing the twist)

I'll start with two obvious ones:

If you're revealing the twist or discussing it in your replies, please use spoiler tags

To use spoiler tags:

You do a > and a ! with no spaces then add your spoiler and end it with a ! and a < no spaces

Looking forward to discovering some great twist episodes I haven't listened to yet