A Mai Tai (was) my code co-pilot.
Somewhere 32,000 feet over the Pacific Ocean (during a 5.5-hour flight to Hawai'i), my laptop battery finally gave out while I was prototyping a browser-based tribute to an old Commodore 64 space-themed shoot-'em-up I used to enjoy.
(There was no in-flight wifi available, so boredom lead to clicking around idly, running the old VICE C64 emulator with some games, and an "ah-ha, I've been meaning to do this project at some point" moment.)
I didn't have a pad of paper handy, so I carefully-unfolded the paper of a pack of gum and got to writing basic routines, object, method and property lists.
Back in the 80s, I used to write and edit code like this when on vacation, family road trips and the like, and then I'd enter it all on the computer when I got back home. Laptops have largely changed this these days, but I'll admit it was fun to revert to old habits.
I have a sort-of working prototype now, and will eventually post some screenshots or something.