I had an f-bomb in shipping source for over a year before I noticed it. (Was a chunk of code that had been object file only then we switch to shipping source.)
Somehow it even got through the lawyers' Bad Words filter.
i only add obscene comments on my personal stuff -- but whenever i'm trying to debug a hard problem, i will add a logger.debug("is this f*ing code reachable?").
i just have to make really really sure i don't commit these kind of changes.
However, the pervasive wtf undercurrent here in the comments actually makes it colorful yet oddly not too distracting. I like it.