When you're playing nine player sit and go tournaments there is always going to be large stacks and short stacks throughout the tournament. As the blinds increase, players decrease and stacks become further spread out you need to be ready to loosen up your game. If you're one of the two large stacks at the table then you need to be ready to make some clutch all-in decisions.
As sit and go tournament blinds increase players with the short stacks become less patient and start going all-in with almost any connecting cards. This means that there is a good chance you could have a better hand then the short stack and if you don't then you're usually in good shape. When you're against two live cards and you also have two live cards then the odds are nearly a coin toss and you have a good chance of winning the pot.
This means that when short stacks begin pulling the trigger and throwing their chips in the pot you need to determine whether or not the odds are worth calling. If you have a good hand then you should obviously call the short stack as they usually won't have a monster hand and you'll win the pot. If you have a marginal hand then you need to consider the odds of calling the all-in and if there in your favour then you need to make the call.
Example
Now say you're big blind and the blinds are currently at $100/$200 which are fairly high for these sit and go tournaments. If everyone folds and the short stack is in small blind and raises you all-in then you need to make a decision on whether to call or fold your hand.
The short stack goes all-in for a total of $695 which means that you still need to make a call of $495 or fold your hand. Since you're getting almost 2-1 on your money this one should be a no-brainer and you should make the call. Whenever you're getting 2-1 or more on your odds you're almost forced to call with nearly anything.
As long as you have two live cards then you have a great chance of winning the pot and with suited connectors it opens your options right up. Sit and go tournaments are best played by aggressive players so if you can't see yourself making calls with marginal hands then you probably should stick to cash games. In sit and go tournaments the blinds rise until someone's wins the tournament so if you sit around waiting for a monster hand the blinds will eat you up.
If you're lucky enough to get a large stack then play it right and try to increase your lead on the rest of the competition. If the odds are in your favour to make the call then take the gamble and try knocking out your opponent. I typically make the call on anything better then 2-1 odds if I'm the large stack going against a short stack.