At work, we often wind up sharing systems. Multiple people will be doing things on the same system at the same time, or we'll borrow each others' systems to run tests. This reveals each of our quirks really very clearly....
The guy who always creates an enterprise user (one of our user types) with the name "Kirk".
The guy who comes in behind him and creates another user named "Picard".
The guy who names things starting with "moo" (e.g., "moo1", "moo3").
The guy who names things thematically after fruit (e.g., "banana" and "apple" and "pear").
It's fun to look at a system that's been around sometimes and see our fingerprints on it. It's actually useful, too, because you can look at a system that's doing something unexpected and ask the previous user about it; because we have the fingerprints we know who to ask!