[cardcounter0]

Face up game works best. Sit at 3rd base. If you are dealt a good double down hand, while the dealer is looking at first base and working those hands, place your double down bet.... but place it on top of your original bet.

When the dealer comes around to your hand, they will notice this, and place the bet properly, and yell at you. Feign like you don't know what you are doing and apoligize.

Or the dealer doesn't notice and motions for you to make your play, at which time you can double down again, matching the doubled stack for an effective quadruple down.

Do it more than once or twice and get caught, by the dealer, and at the very least you get thrown out.

Get caught by the eye in the sky, and you are looking at 2 years in the State Pen in Nevada. It is a primitive form of bet capping and strictly illegal.