Some college-aged kid got smacked in the face with a golf club, breaking a bunch of stuff that required a fair bit of surgery to repair. Kid shows up a couple of weeks later leaking spinal cord juice from his nose and complaining of headache. He is diagnosed with intracerebral pneumocephalus (IP), which is doctor-speak for having air inside your brain. Back to the OR he goes, where they somehow get the air out of his brain.
Perhaps unsurprisingly, IP is usually the result of being hit really hard in the head with something. Not only do you have to fracture your skull, you also have to tear the dura mater and arachnoid mater. Apparently one of the possible symptoms of IP is hearing a splashing sound akin to liquid sloshing around in your head whenever you move it.
Oh, and here’s a photo of IP: