The one on which the ring fits.
No.
I wear a thumb ring because I love the way it looks. That's all.
Fashion
Because he is mentally handicap.
you wear it on your thumb
This means when you are not married just wear it for fun!
It means nothing
People often say that if a man wears a ring on his thumb it makes him gay. No, having sex with other men makes you gay. A plain silver ring in my opinion can look good on some men's right thumb.
I'll describe: on the left hand (counting from the thumb {as 1 thumb, 2 index finger, 3 middle finger, and then the fourth is where you wear the ring on})
It menas she is married ,but available for sex
It was her fathers wedding band