What is Something Up Your Sleeve?
1.
Poker players who were (or are) less than honest, were known to keep an extra Ace or two stashed up their sleeve. This could be retrieved when needed either by means of slipping it out or by a spring loaded mechanical device that would slid the card out when pressed.
Everybody put your hands on the table. Slim, I think you've got something up your sleeve besides your arm.
See
