Morphing Mana Mania

At the beginning of each upkeep, lands that produce white mana instead produce red mana, lands that produce red mana instead produce green mana, lands that produce green mana instead produce blue mana, lands that produce blue mana instead produce black mana, and lands that produce black mana now produce white mana.
This gem of a spell is often found by my peers to be bizarre, but it is a hoot at parties.... and inter-planar conflicts for the fate of all existence.