These balls are dangerous. I highly advise keeping them out of your home if you have small children.
My 6 yr old's finger was so purple and swollen. He was screaming and crying. I was so afraid. My 18 month old was also hysterical at the drama of it all.
I cut it off just like this lady's blog says. I cut the ball in half and cut chunks of the ball away until it was just a thin ring on one side. Then I had to hurt my little one a bit when I stuck the tip of the scissors between his flesh and the leftover ring. He screamed for the few seconds until I cut it.
He is fine now...finger is still swollen but recovering fine.
I googled "Wiffle ball and stuck finger" last night and found a few stories of the same incident...all ended in the ER or with the fire department. We were lucky.
His finger is still red and a little swollen today. No pain, it is doing fine.