I don't mind them having a laugh but swearing?
Given the replies to my original post I now wonder if the crew may have been on a ferry flight and put that into the FMC not being aware it got transmitted.
As for SBS being "potential for rather undesireable uses", you could say that radios and ACARS decoders would come under that heading but I don't think that's been the case, although I await corrections if I'm wrong.