"Hungry Snake...." joke

Having arived at the edge of the river, the fisherman soon
realized he had forgotten to bring any bait. Just then he
happened to see a little snake passing by who had caught a
worm. The fisherman snatched up the snake and robbed him
of his worm. Feeling sorry for the little snake with no
lunch, he snatched him up again and poured a little beer
down his throat and went about his fishing.

An hour or so later the fisherman felt a tug at his pantleg.
Looking down, he saw the same snake with three more worms
in his mouth...