I once left mine and when I went to the toilet ninjas leapt out of my mini-pretzel snack packet and overcame the guy sitting beside me, stole my Macbook Pro, and parachuted to freedom.
If you're wondering how I got it back from the Ninjas, the answer is simple, I went to my local Apple store and spoke to a genius. She told me to go to a coffee shop, look as cool as I could without a Mac and by the time I got back a crack team of Geniuses will have neutralised the ninjas and returned with my MBP.
As it was written so it was done.
Whenever I fly I now leave my MBP sitting on a landmine when I go to the toilet.