It reminds me of the time I dreamed that I was eating mini-marshmallows and woke up to find one of my earplugs missing. It was rather distressing to think that I might have swallowed it in my sleep. And I was really thirsty when I woke up, but I was afraid to drink anything in case the earplug soaked up all the liquid and expanded in my stomach and then I'd have to go to the hospital. Luckily, after about twenty minutes' worth of worry, I found the earplug in my bedclothes. No hospital stay necessary, thanks.
If I did swallow that broken plastic, I wonder what kind of damage it could do. Of course, I have watched enough doctor shows on TV to make some assumptions. Like it could get embedded in my stomach, or perforate my intestine, or... hey! I think there was a House episode about that. So if I come down with some mysterious disease, make sure you tell the doctor about the broken fork.