Two… one to tell the engineer to do it, the other to say "I don't know, what do you think?"
or
The question is irrelevant, since you couldn't find the dolls even if you knew how many. (Note: Well, this was a good joke in 1983-84. . . .)
or
When it's ajar!
or
I've been framed!
or
2 years old.
Cow: "Mooooove over"
Sheep: "Naaaaaaa."
or