One possibility is that it’s a simple substitution cipher (like Caesar shift or Atbash) or a phonetic respelling.
But the most plausible is it’s a phonetic/joke spelling of: — but that’s not quite right. thmyl drayfr san fransyskw llayfwn
Given the time, I’ll guess it’s meant to be a whimsical, coded way of saying: But that doesn’t make much sense. One possibility is that it’s a simple substitution
