By Jove, I think I've got it!

Just got this joke from a knitting pal:

I'm a chaplain at the County senior citizens' home. The other day I saw
a 96-year-old lady knitting a sweater for her granddaughter.
"What kind of yarn are you using?" I asked.
She said, "Virgin wool."
"Where do you get that," I asked.
"Ugly sheep," she smiled.