The first thing I asked my colleague in the office when I received this message was if Safaricom maintains any demographic data on its clients. We guessed that maybe they do and they have profiled their customers somehow to know who would be tickled by such a message. Clearly we were wrong. They really should know better next time. Shame on them!
That being said, I honestly see no problem with the 5 bob part. What irks me is to think that exactly the same intimately suggestive message that was sent to teenagers, is the same one that was sent to their parents, their grandparents, their teachers, their pastors... Aii? That was dumb.
Learn first to treat your time as you would your money, then treat your money as you do your time.