Desk workers of Lemmy, what are your tips for appearing busy in the office even when you might not be?

Terminal -> vim with syntax hilighting -> some source code. Passerbys won't know what your code is for or what it's supposed to do, but it'll make you look busy and you can tinker with your own projects.

A friend of mine has a highly complex spreadsheet open at all times at work. He's a D&D DM and uses that sheet to easily calculate price fluctuations in finished goods based on changes in resource price.