I am a 21 year old caucasion male and rather hairy. Not overly hairy, but enough to be considered hairy. The hair on my legs (specicially the thighs) are each about 1/2 inch to 3/4 inch, but today I just noticed a hair on the side of my thigh, about midway between the hip and knee that is at least 3 inches! This is something I would have noticed yesterday or the day before, so considering I never noticed it, it makes me thing it literally grew that much in the last 24 hours. The hair is gray, however when I tug on it, it is healthy and not coming out. (I don't want to pull it out because I NEED to show this to my girlfriend!)

This has never happened before, its not only my first gray hair, but my first hair longer than 3/4 inch (besides on my head). My hair grows very slowly as it is! how could this have happened? I almost feel like I could have watched this grow when it was happening because it was so sudden.

I notice loose hairs and long hairs (from my girlfriend) all the time on me, and it bothers me a lot, this is how I noticed this so quickly. I just thought it was one of her hairs stuck in the bed until I realized it is attached to me. I know for sure without a doubt that it is attached to me and not just stuck on me.

Could it have been growing beneath the skin for the last few months causing it to not fall out and all of a sudden it came up to the surface? could I have eaten something to cause one hair grow really really fast and really really long?

For clairification, it is on clear skin, no moles, blemishes, cuts, sores, marks or anything. It looks just the same as any other part of my thigh. The hair around it is just as normal as any others, and there isnt any bald patches there at all. I'm not worried, just curious

Hair grows approximately 1mm/day - there is no way a it could grow 3+cm is a day. You must have not noticed it and the fact it is grey makes that very likely since it would be far less noticeable. As an aside hairs do not "grow" beneath the skin nor does a food cause hair to grow faster.