After arriving in Lagos in the middle of the night, and you've left the relative "safety" of the airport and you're en-route to your overnight accommodation, driving through the back streets because the driver knows a quicker way (of course!), don't be surprised to be waved down to stop in the very dark of night by a small group of unidentifiable very dark people carrying very dark and dangerous looking AK47's. The question going through your drivers mind is, is this a legitimate police road block (and stop), or are they some ruthless thugs expecting an easy picking (so keep going, faster!)? Do you trust the driver with your life to make the correct decision? If he stops and they're not cops you get whacked, and if they are cops but he guesses they are just some friendly locals on a good night out so keeps going, you get whacked.
Life hangs in the balance with a decision made in an instant by someone else.
This is one of my first memorable experiences of working in Nigeria, of course there are plenty of others. If you're considering going to Nigeria then get street wise, and quick, your life might just depend on it. You also need to ask yourself, are you street wise enough, and is it worth it?