I hurt mine doing dumbbell shrugs. Only on 1 side though, and at the time of doing it, I didn't think anything of it and just continued working out. The pain only came afterward, when I couldn't turn my head, look down, etc. I thought it was serious, so I took a week off from any physical activities, and with 3 chiropractic visit's during that time frame, I was fine the next week and haven't had any problems since.
They told me I strained a muscle (no shit), but because it's near to the spine and in turn all these nerves, it makes it feel alot worse than it really is.