A few years ago, I flew EBL-VIE-ZAG, and woke up the next morning in Zagreb with some sort of intestinal mess from hell. Complete with seeing stars and hallucinating. Somehow, my ex managed to get me back home to London that day, where I more or less slept it off over the next 24 hrs in between frequent all-night dashes to the WC.
Felt good enough the next day (aka functional) that I made it to LHR for the flight back to DC. But not good enough, however, to even remotely consider airline food...business class or not.
About halfway through the flight (United 777) the pilot came back to me, and asked to have a word with me:
"The crew tells me you're not eating, and you're spending lots of time in the bathroom. What are you up to in there? You're not up to anything suspicious are you?"
I think he thought I was on some sort of crazy fast before I, um, committed a Richard Reid.
You should see the shade of red he turned when I explained to him what was really up....