If you press "S", the batter will spit. If you continue to press it, you will eventually see the the cards.

In order to get this to work you first need to enable Commisioner mode. Do this by clicking on the options tab in the right-hand corner or by editing a player.

Now go to the trade screen. Your team's logo should be the top logo. Change it to the team that you want a player from and change the bottom logo to your team's logo. You now can nab any player you want for nothing. You can also do this with points too.