I remember this well. It's one of those jokes that circulated widely and really highlighted the absurdity of the entire 1984 referendum.
The punchline went like this:
The joke was that after Zia saheb went home following his speech—the one where he graciously thanked the people of Pakistan for "electing/selecting" him as President for the next 5 years—he was quite pleased with himself.
During the speech, he had made a grand gesture with one hand, holding all five fingers stretched out to signify his five-year term.
When he got home, Mrs. Zia was cross with him. She reprimanded him, saying: "Why did you only show five fingers? Next time, you must show all ten fingers!"
When he asked why, she replied, "Five years for yourself, and five years for me!"
It was a telling sign of how the public viewed the entire process—not as a democratic mandate, but as an assured continuation of personal, long-term rule.