It is not done in "polite society."

I spat in my hand.
I did.
My mom told me to do it.
I was working on the baby blanket (that never ends!) while visiting her and she helped me tuck in the loose ends where I started new skeins. And then she mentioned that she'd heard of a trick with wool where you spit in your palm and rub the two pieces together causing them to 'felt' together so that no ends stick out and you can then just knit the new yarn in, no knots.
So tonight I tried it.
And, well, it worked! No pokey ends. But it can't be synthetic, only real wool.
However, next time I do it, I'll brush my teeth first. Nothing like your bad breath mushed into your palm.