I had came up with 2 rules of my own, although of course the chess world will never see them.
These are as follows:
If one of your pawns has not yet been committed to the battlefield i.e. still on it's "home square"
then it can simply be removed from the board.
This is called a 'dismissal', possibly noted as, say for example Df2
if White wished to remove the pawn on f2 to open up the castled Rook's file.
This move drops a pawn, but could open up lines of attack against the enemy King,
and which can be played at any time (except if resulting in check against own King).
To spice things up a bit, a Knight or Bishop on the 7th rank (opponent's 2nd rank) could be demoted to a pawn,
and so being one step away from Queening.
I've given this one less thought than the 1st rule, but sounds fun either way.
Anyone else have any wacky rule ideas?