What do you do when you leave your computer/laptop at home while you visit family for the holidays? I always do this, thinking that it'll be better to spend some quality time with the family, but there are moments where people are doing their own thing and I wish I had a laptop to play with some code.
These days of course many of us tote around tablets or large phones, so there is some potential for hacking or at least learning about new programming techniques. One of my favourite apps is actually Vim, which you can get for iOS and Android:
To the uninitiated, Vim for a touchscreen sounds horrible, but it's actually pretty good -- because it's modal you can enter Command-line mode with : and leave with the escape key easily enough. If you're an experienced Vim user then it can be revealing to think about the mnemonics for commands rather than relying on muscle memory.
I also found that the big programming video services have iOS and Android apps, so you can study a new programming language, framework, or library:
Apple and Google's book stores also sell many technical books from the popular computer science book publishers, so you should be able to find something to do while your parents argue and your partner is walking the dog, wrangling toddlers, or snoozing after too much turkey.