Vegas Stakes (GameBoy) weird easter egg demonstration, previously undiscovered
This game have very odd easter egg. There are some random events interrupting your game sometimes, no matter what casino or game you playing. One of the events is "BOXING ON TV". When this event is happens, you've asked if you want to make a bet on boxing match, then the TV is displaying the same animation of boxers no matter who actually will win. During the match, hold A + B + Up + Left then wait. In the end, left boxer additionally will hit the opponent a couple of times with fast hooks. That is all the difference. This is does not affect the match result also.
Look at the top-left side of the screen, when the second part of video is playing. There the pushed buttons will be displayed which caused the difference in animation.