Back in the day… early 90’s, before the interwebs was really popular, I was a travel agent, using Sabre, which is/was (I’m not sure now) American Airlines’ reservation system. Those confirmation codes are more commonly known, in the industry, as record locators. Pretty much anyone on the system could retrieve anybody’s record by record locator. When I was bored, I would pull up random record locators, by typing in words of the correct length (I believe they were 6 or 8 chars long) Doing this, I found a number of records in which American Airlines employees would chat in the comments fields. I joined them and made some friends that way. The way it works is you would add some comments to the bottom of a record. Then you save the record, and others would add their comments.
bookmarked not for the funny haha, but the awesome story about using sabre as a BBS of sorts for bored travel agents