Zaphod, as was his custom, was still drunk. He was chatting animatedly to the wall, which he happened to think was Eccentrica Gallumbits.
"Really, Eccentrica," he was saying, "we should go sightseeing together sometime. There are so many bars...bars? WHERE DID MY PAN-GALACTIC GO?!?!?!" he yelled, forgetting entirely about the wall/Eccentrica. In answer to his question, he was suddenly hit in the back of one of his heads with a large, heavy object.
"Ow," he said stupidly.
"Is this what you were looking for?" Trillian asked, waving a solar- system sized bottle in his face, which, coincidentally, was what had hit him in the back of the head.
"Yeah," he said, blinking rapidly at the stars in front of his eyes. He reached for the bottle. Trillian handed it to him. He attempted to dump it down his throat until a startling realization hit him.
"It's empty," he said dejectedly, "there's a bottle of Old Janx Spirit under the computer over there. Would you grab that for me?"
"No there's not," Trillian replied. "I threw it out the window."
"Oh, okay, I see, I'll go...you did WHAT?!?!?"
A comprehension had hit him, this time in the back of his other head. This comprehension came in the form of a bowling ball, and he was knocked out.
"Second time today, seventh this week," Trillian muttered, "We're really going to have to do something about that Improbability Drive."

At this time, Ford had escaped Trillian's attempt at sobering Zaphod, and was working with a computer in a back room.
"If it takes forty gallons of Gargle Blaster to..." he was mumbling to himself, "and I am sixty-seven out five thousand four hundred and forty- fourths the size of a..."
Out of all of this, he concluded that it would take him four seventeenths of a gallon of Pan-Galactic Gargle Blaster to become intoxicated to the point that Zaphod was now. He ran and got a bottle.
"If misery loves company," he said, "then I am quite positive that Zaphod does too."