Is there anything I can do to one of my testicles that isn't horribly painful/dangerous that will damage it enough that a doctor will have to remove it? I've desperately wanted to have one of them removed for years and want it to look like it was an accident or something rather than having the doctor look at me like I'm completely crazy.

Well, you probably are technically "crazy". I'm not saying that there is anything necessarily wrong with this, but self-harm is a type of body dysmorphia or other mental problem. It may be that completing the act is the least harm, and in that case the medical community might help you.

In any case, you didn't really give a reason for why you want this. Even for this board your request is a bit odd. Guys that want full castration often have a hormonal and/or aesthetic reason -- i.e. they don't identify as male, or they want to lessen their sexual urges, or they are worried about being a sex predator, or have already heavily modified their genitals for body art reasons or shock value. There are others that want it due to masochism or experiential fantasy (i.e. the idea of the act is what excites them, not the result) -- that is not really a good reason for seeking castration.

Can you explain more about why you are so interested in a one testicle situation?

Regarding damaging the testicle, what have you already tried? Obviously there are several ways to do it. For the one that has consensus for being most safe (not totally safe though), you should look at the thread about alcohol injection.

go to a female urologist

they never think you are crazy

or at least they never verbalize it to me anyway

all you have to do is complain of chronic pain in the testicle

50 percent of doctors will remove it since it is just one testicle

that was my experience anyway

you can always have multiple vasectomies done..that will mess them up...they never check to see if you had a vasectomy done before