So I finally finished a level of my own. It's called "Men's Room Etiquette" and it tests you on your intuition and understanding of the unwritten rules of urinal selection.
I ran into a bug while I was making it, though: after a certain point, whenever I tried to put a mouth on something, actually entering text would cause my popit cursor to freeze. Consequently there wasn't a good way for me to actually explain the unwritten rules in the level itself, so they're here instead.
[spoiler]The rules are as follows. Each rule supersedes the rules below it.
1. Don't stand adjacent to other urinal users.
2. Don't stand adjacent to the sink.
3. Don't force subsequent patrons into breaking rules if it can be helped.
4. When several people are already using urinals, it's best to pick a spot such that, if one of those users were to leave, a subsequent patron would be able to break as few rules as possible in his urinal choice.
5. When all else fails, select the urinal as far from the sink/other users as possible.[/spoiler]