I think the fact that lots of people immediately think 'their own ghost' says that this is a poor choice as it's too obvious.
Some people are absolutely terrified by turkeys. I also think I saw a youtube video where a woman was reduced to a sobbing wreck by a kitten. Since your book is a comedy, maybe you could make a funny backstory about why this guys is terrified of something small and cute.
It could be something serious or something silly. How comedic is this story? And how comedic is the scene supposed to be, other than the accident which is obviously amusing.
Some kind of reaper maybe. It could then be connected back to him dying. The only problem is that's kind of a set up for future encounters with the overdue death collecter trying to reclaim him.
It's not going to be "Hitchhiker's Guide" level comedy (even if I were capable), but more a traditional noir-ish story with the absurd twist. Since the MC is kind of a tough guy, I want whatever scares him to be scary to the reader as well, so he needs something recognizably Really Bad to panic over, even if it turns out to later be not as big of a threat as he thought....and writing this has given me inspiration. A creepier than average ghost. Ghost is creepy, but ghosts can'taffect the physical world, why is the wallpaper suddenly splitting over there with blackness pouring out of it, what kind of new manifestation is this, get me the hell out of here, pentacle, hello GG. Later the local exterminators perform their own exorcism on the cockroaches that MC mistook for Satan himself. No "greater magick" chasing him through the rest of the book. Sound terrible?
I can see it. His mother's nagging him to get a better job then ghost hunting and ironically she's a ghost to.
Thanks for the nightmares. As to what scares the guy? Don't, don't, don't make it a generic creepy crawly. Make it something that will scare our GH and no one else. Make this scene centric to his character, make it reveal something so that your readers get more interested in this ex marine. Poll a war veteran if you can. But that's just my five cents.
I like the previous mention of his fear being related to how he died the first time round (for some reason I'm not able to quote the post ). Alternatively, how about something that happened whilst they were in the marines? For example, perhaps he has a fear of drowning, or of being involved in combat?
