Never ever EVER put bad language in any unexpected error cases or logs - even as you're developing it... it WILL somehow magically make its way to production, and it WILL appear!
Not only will it manifest itself in production, it will do so at the time and with the user most likely to cause great embarrassment.
[NB There is a related phenomena to do with a demo of a system that includes "adult content" (i.e. porn) - the likelihood of a user randomly stumbling upon this content is practically 100%, even if this content is a tiny part of the overall demo].
I remind myself frequently not to swear in code as I am quite juvenile on a normal day. If I'm struggling I'll just make up a word, so that if it ever happens that someone else sees it I can say it is an acronym but that I have conveniently forgotten for what.
I had a hearthy chuckle when learning about Android's Log class: the highest level of importance for a message is WTF. Documented as What a Terrible Failure.
Wow, deja-vu, this is just what happened to me one time when I was working on a new booking system for a hotel.
I was working on site over the winter season when the hotel was closed down, a lovely old hotel high up in the Rockies. Every day I sat down and wanted to write some brilliant code but all I ever ended up writing was the same comment
All objects and no functions makes Jack a dull boy.
over and over again.