I don't know why, but for some reason there seems to be a rather large amount of euphemisms for jerking off that allude to various animals.
To name a few:

• spank the monkey
• beat the dog
• baste the turkey
• choke the chicken
• chop the lamb
• strap the snake
• wax the dolphin
• pound the pelican
• feed the ducks
• shear the sheep

What is up with this? And of course, there are a select few to describe the female anatomy as well:

• stroke the kitty
• feed the beaver

Am I forgetting any?