Funny!
A few months ago I was flying Southwest BUR - OAK...my flight was delayed 3 hours, but during that 3 hours there were 2 other BUR-OAK Southwest flights scheduled, so almost everyone switched to one of those.
When it came time to board, they didn't call A-B-C.. they said "okay, all 15 of you that didn't get on an earlier plane... time to board".
It felt so empty!