Douglas Adams wrote ... that he wanted Slartibartfast's name to sound very rude, but still actually be broadcastable. He therefore started with the name "Phartiphukborlz"...
...
"One thing I don't think I explained in the script book was that I was also teasing the typist, Geoffrey [Perkins]'s secretary, because ... she'd be typing out this long and extraordinary name which would be quite an effort to type and right at the beginning he says 'My name is not important, and I'm not going to tell you what it is'. I was just being mean to Geoffrey's secretary."
That's fantastic and I don't doubt for a second he was being a smartass with his friend's secretary. Hell, the first book was begun on a hillside in Amsterdam after plural bottles of wine and who knows what else. Makes perfect sense.