What strange chess rules can you think up?

If the opponent has no pieces left except for the king, and you have more than 15 points in material, you have to reduce it to at least 5 points in material. But you can choose which pieces to use. Only allowed 1 pawn for your conversion. 

In college we had different people accidently make moves we remembered and named for them.  The Porter Knight (y.t.) could move two squares on a diagonal.  A Lewis Bishop could drift to a new diagonal after moving a minimum of one knight's hop away (Bf1-e3 or Bf1-d4 is OK, not Bf1-f2) and could give a solo mate in the corner while a Villivaso Rook could drift to the next rank or file after moving at least four squares and from the edge of the board could deliver an open board mate if the king was not in the center. 1. Kf5 Ra5# but 1. Ke5 Ra5+ is only check (Kd4 or Kd6 since the rook is too close).  Played a game where each side was allowed to play one move each by a PN, LB, or VR.

This strange rule doesn't compare to the ones posted, but if a pawn captures a piece, you keep moving until no pieces are captured.

If you don't look happy while playing, then you are not eligible to play chess.

Lol, if you are legally blonde then you must go first!

!  Yay, then I'd go first every time!

Nice and blondes have more fun (while playing chess)!

If your knight captures another piece you must use a lasoo.

If your knight captures another piece you must use a horse.

The strangest rule is "a knight on the rim is dim"... I often find that putting a knight in the rim is a good idea...

You should be forced to resign

There should be a line of judges that all need to flip a switch which turns on a light (pick your color) which indicates the end of the game.

When you check the opponent's king, you shouldn't say "Check". That word is banned and can no longer be used now. Instead, after making the move, you have to stand up and dance gangnam style.

Interesting... But I would consider allowing pieces [not just pawns] to capture pawns en passant.

How about the roles of the King and Queen be reversed, its the Queen you have to checkmate and the King well, its useless isn't it with its "one square" movement lol But however, as ever, the King cannot be captured, but the twist is it cannot be captured by minor pieces or the Queen and King of the opposing team itself, except by pawns. 

Should make a fun game 

In the beginning of a game, each player have a ghost. The ghost moves like a king, but can teleport when is near a king. When teleporting, it cannot take any piece. Ghosts can also teleport near knights, but the cost is the knight must be destroyed. If near a pawn, It and the pawn can merge into a ghost pawn. Ghost pawns move like normal pawns, but can only promote to kings. Normal pawns can also promote to ghosts.

Cylinder chess, the h-file is next to the a-file.  Na1-g2 or Na1-h3 is possible and on an open board a diagonal might run from f1-g2-h3-a4-b5-c6-d7-e8.  Note a bishop controls the same squares on b5 as it does on f1, but can't be captured there (if it's on f1, of course).

These ideas mainly seem to be what I once knew as 'fairy chess' rules.  I was thinking the en passant rule could change to be more logical in 'real' chess.

Once your king reaches the 1st rank of his/ her enemy, you win the game. (Derived from the rules of the Game of the Generals)

Here's one I came across a couple of days ago or is something like it. 

Whenever you play chess, you must have a group of real people being set up beside you like real chess pieces.

Each time you capture a piece, the other player must push the other player that represents the piece to the ground within 30 sec in order for the capture to be succesful. If the piece is unsuccesful, the piece that get sent to capture will be taken off the board and the piece that gets captured remains on the board.