From a fascinating article about Squirrel Masturbation from Discover Magazine:
Hairy little guy sucks himself off and eats his load - I love it! Isn't science grand?“An oral masturbation was recorded when a male sat with head lowered and an erect penis in his mouth, being stimulated with both mouth (fellatio) and forepaws (masturbation), while the lower torso moved forward and backwards in thrusting motions, finally culminating in an apparent ejaculation, after which the male appeared to consume the ejaculate.â€
Apparently these fellows have dicks almost half as long as their bodies (damn - mine would be almost 3 feet long) so sucking themselves is probably inevitable.
They also have HUGE BALLS:

You can read the article here - it's a good read:
http://blogs.discovermagazine.com/notro ... nfections/
Go squirrels!
Al