What is the longest delay you have ever experienced?

Today I am supposed to be flying from Launceston to Melbourne but there is some heavy fog around and all the flights before us are starting to get delayed longer and longer. This reminds me of the time I was delayed 3 hours and ended up arriving at my destination just before midnight! So I was wondering what is the longest you have been delayed?

Probably should be in #real-world-aviation :)