The general rule in tech comm is to avoid humor, and I think the main points of consideration are: audience, context, and localization - if you're considering this at all.
Speaking specifically about the localization concern, the translation of idiomatic language is an important consideration, but another significant concern is cultural interpretations of your humor.
I saw as interesting presentation at LavaCon last year where Jon Ann Lindsey, a Content Strategist from Google, spoke about their own attempts and research on this.
In synopsis: Google encourages their staff to be "Googly" and they did a large case study where they had focus groups from something like 40 different countries look at their documentation and actually had someone sit down with these groups in person to get feedback. They found that even the most minor humorous references (for example a picture of a cute penguin from their image library that was used in their documentation of the same) came across poorly in many regions. Some of this was unfamiliarity because people from some countries may have never seen a penguin. Others found it just plain infuriating and inappropriate that someone would try to insert "humor" or "cuteness" where they were trying to get technical information.
My major takeaway from this was: know your audience. If you're localizing content, this is even more difficult and imperative. Unfortunately, many of us don't have the same resources that Google does to conduct this type of research on a global scale, so it's probably best to stay in the realm of the cut and dry.