Well, instead you're enraptured by a documentary on sloths. You still get Slack for watching TV, but not as much. You only need one die to play, a single six-sider. Most commonly, you'll be rolling for your income if you have an unsteady job like Temp or Waitstaff. You'll also need a heap of counters to represent Slack.
Pennies work well, as do poker chips.
You can call as many people as you like in a turn, provided you have their cards in your hand. The people who don't provide Slack will always come over. Usually you play them on your roommates and they eat their Food, drink their Booze, smoke their Weed, disrupt their RPGs, or hog their computers. The people who do provide Slack might be busy. If you roll a 1 or a 2, they aren't home when you call.