A guy is stranded on an island with only a Doberman and a pig for company. There's plenty of food and water, and the weather is beautiful, so he's doing alright - but after a few months he gets lonely...
The pig starts to look more and more attractive - soft, pink flesh, round buttocks, etc. But every time this poor guy makes an advance towards the pig, the Doberman snarls at him and once almost bit his leg. Very frustrating.
One day the guy sees a speck on the horizon, so he swims out there and it turns out to be a dinghy, cast adrift, and in the bottom of the boat is a beautiful woman, unconscious. He drags her to shore and brings her into his hut and slowly nurses her back health. Finally she is well enough to walk and she says to him "Thank you, thank you for saving my life. I don't know how I can ever repay you. I'll do anything for you, anything, just name it."
The guy thinks for a minute and says, "Would you mind taking my dog for a walk?"