This has had 10,000+ YouTube hits, so maybe you've seen it before but it's here because this particular dog has clearly read my earlier post, Beating Yourself Up for Fun & Profit, and is no doubt channeling his inner Donald O'Connor, Michael Richards, and Rowan Atkinson. And why not? Fighting yourself has to be one of the quintessential slapstick gags: it's physically difficult, it's mime, it's absurdist humor.... it's barf-irrific.
Guard that bone! Yes, animals do have a sense of humor.
Thanks to Ted Lawrence for the link!