As you know, the male surgery is not invasive, and not nearly as serious as for the female.

While it would be nice for him to stay calm, well, you've seen what HE thinks of that! Obviously he had no lingering effects from the anesthesia, either.

Is he on pain meds, or wearing an e collar? Is he licking the area at all -- that would be the most important thing to watch for.

It's been 14 years since I last had a male fixed, so I'm hopelessly out of touch at this point, can't be more specific, sorry. (Wow, Chestnut is 14?!) (I should say, a male who wasn't a feral and hence hiding in a cage to start with)