...at least, it provides for a nice analogy to use when discussing basic security concepts. I don't think people necessarily choose better passwords after a skinful, nor do they usually make improved choices of what information to share on social networking sites when returning from the pub. That's probably why Mail Goggles exists.
So, the attendee beer bash at WWDC. There is beer. There is also the regulatory framework of the state of California, which mandates that minors under 21 years of age may not be supplied with beer. There are also student scholarship places to the WWDC, and no theoretical minimum attendee age. There are also loads of people in the vague area of Yerba Buena Gardens who are not attending the WWDC. But only attendees may visit the bash, and only attendees over 21 may drink beer.
I went to the registration desk at Moscone West on the day before Phil Schiller's keynote, and identified myself as Graham Lee. "Hi, my name's Graham Lee" I said to the lady behind the desk. It turns out that's not sufficient. While I did indeed give the name of someone who was indeed registered to attend the conference, there's no reason for the lady to believe the identification I gave her. She wants to be able to authenticate my claim, and chooses to rely on a trusted third party to do so. That third party is the British government (insert your own jokes here), and she is happy to accept my passport as confirmation of my identity.
Now I am given my attendee badge, a token which demonstrates that I have authenticated as Graham Lee, an attendee at WWDC. When I move around the conference centre to get to the sessions and the labs, the security staff merely need to look for the presence of this token. They don't need to go through the business of checking my passport again, because the fact that I have my token satisfies them that I have previously had my identity authenticated to the required level.
The access token would be sufficient to get me in to the attendee beer bash, as it proves that I have authenticated as an attendee. But it does not demonstrate that I am authorised to drink beer. So on the day of the bash I go back to the registration desk and show a different lady my passport again, which indicates that I am over 21 and can therefore be given the authority to drink beer at the bash. I am given the subtle green wristband pictures, which again acts as a token; this time not an identification token but an authorisation token. The bar staff do not care which of the 5200 attendees I am. In fact they do not care about my identity at all, because they know that the security staff have already verified my attendee status at the entrance to the event - therefore they don't need to see my attendee pass. They only care about whether I'm in the group of people permitted to drink beer, and the wristband shows that I am in that group. It shows that I have demonstrated the credentials needed to gain that particular authority.
So, there we have it. A quick beer of an evening with a few thousand colleagues can indeed turn into a fun discussion of the distinction between authentication and authorisation, and how these two tasks can be carried out independently.