Because E.T. eventually went home!
or
Just one, but he/she will spend hours checking for technical problems.
or
Fish and ships.
or
You're Hired.
or
Discrimination.
or
The Flea Stooges!
or
Does it have to be a light bulb? I've got this neat candle holder...
or
One who knows how to play the saxophone, but doesn't!
or
None, because they were copycats
or