Not enough cement.
or
Two lawyers were fighting over a penny.
or
The vacuum cleaner has the dirt bag on the inside.
or
The bucket.
or
Accountants know they're boring.
or
A prostitute will stop screwing you when you're dead.
or
Only three. The rest are true stories.
or
A vampire only sucks blood at night.
or
They make used car salesmen look good.
or
His partners.
or