How To Survive In The Real World, Rule #4

The three words, "I DON'T KNOW" is a very powerful sentence. Just these three words alone possess the ability to piss somebody off big time, to turn somebody off (from ever wanting to speak to you ever again), or just to push all the blame to somebody else (anybody else BUT you):

When somebody approaches you for help:
Friend: "Hey could you help me out..."
You: "I don't know how."

Friend: "Do you know how to get this..."
You: "I don't know."

Your friend, by now (if he/she is still a friend), would probably be darned pissed, and will not ever consider talking to you ever again.

When being accused of something:
X: "HEY!! Why did you..."
You: "I don't know!"

X: "How did things turn out like this???!!!"
You: "I don't know!"

Effectively, you're pushing the blame that is ON you, cleanly AWAY from yourself. The gamble here is that you would be taking a chance with the consequences of shedding all responsibility. But this is rarely something that is life-threatening or just anything that would result in capital punishment, so most of the time, you *can* get away with using the three words, "I-DON'T-KNOW".