Shipwrecked man on an island

A man was shipwrecked on an isolated island with nobody for company
except his faithful dog. Life was getting monotonous until one day he
spotted a sheep on the other side of the island.
Slowly approaching the sheep, he managed to get it into position and
was about to mount it when suddenly his dog gave out a frantic bark
and he had to give up the idea. A second and subsequent attempts by
the man to approach the sheep from the rear met with similar
frustrations.
Then one day, a pretty girl was washed ashore almost lifeless, a
victim of another shipwreck. After some furious efforts at
resuscitation, the man managed to revive the girl.
The girl thanked the man profusely. "I'm so grateful I'd do anything
for you. Anything." she said.
"Good!" said the love-struck man happily, "Can you watch my dog for
fifteen minutes?"