How common/ normal is it to have only 1 testical

It's called monorchidism and is fairly common, but have you been medically checked to make sure there isn't a second undescended testicle? That's also common

Is the reason you can't spell 'testicle' correctly, because you only have half as many as normal people do, so you were only half as interested to learn to spell the word as normal people?

Indict the Douche Bag Clinton

You are known as a "Gelding".

Seeing you cant spell for shit , try calling it nuts or balls and maybe you will be able to spell those 2 words.