I don't know. I didn't think sheep could knit
or
I said, "I've been on telly but I'm no Dean Martin".
or
Three:
One to write the light bulb removal program,
one to write the light bulb insertion program, and
one to act as a light bulb administrator to make sure nobody else tries to change the light bulb at the same time.
or
I rang her up, I said "Did you get my drift?".
or
Because it gave him a big wave!
or
Neither, they all burn shorter.
or