The drunk was floundering down the alley carrying a box with holes on the
side.

He bumped into a friend who asked, "What 'cha got there, pal?"

"A
mongoose."

"What the heck for?"

"Well, you know how drunk I can get. When I get drunk I see snakes and
I'm scared to death of snakes. That's why I got this mongoose, for
protection."

"But," the friend said, "you idiot! Those are imaginary
snakes."

"That's okay," said the drunk, showing his friend the interior of the
box, "so is the mongoose."