I think I met this guy on a UA flight LHR to IAH a few years ago. He had just flown in from IAH and was returning. We were waiting to board and he was an grumpy and fussy. He talked to anyone who would listen. He kept saying something like he was running out of time, had to get as many miles in. I got the impression he "lives" on planes and has no outside life. Yes, he was wearing pajamas!