Original artwork, not a still
So Long, and Thanks For All the Fish ‧ 1984
“Zaphod’s calmed down a lot you know.” “Really?” said Arthur, clustering hurriedly round Fenchurch to relieve her of the shopping. “Yeah,” said Ford, “at least one of his heads is now saner than an emu on acid.”
Behind the line
What it means
Our interpretation.
One speaker reports that Zaphod has settled down considerably, and the listener responds with polite surprise while busying themselves with the shopping. The reply delivers the joke: only one of his heads is now saner than an emu on acid, a bar so low that the good news turns backhanded.
Context reviewed
