6: 2 to screw in the bulb and 4 to testify that it was lit from the moment they began screwing.
or
It held up a pair of pants.
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
Aye, Aye, Arr and the Seven C's
or
they never get old!
or