I know that pinking shears cut fabric so that it does not unravel, but what is pinking and how did the word come into use.
It doesn’t go into quiet the detail you seek, but Merriam-Webster is always a good place to start.
Do you think if I keep quite, nobody will notice?
In Middle English, pynken meant “to prick” or “to thrust.” Later it was used more specifically to describe the stabbing or thrusting motion of a rapier. After that, it’s not a stretch to see how it came to describe cutting a saw tooth pattern on the edge of cloth.
Haj
First, to dqa, I don’t thienk anyone will notice.
FWIW the pinking shears my grandmother showed me have zigzag blade edges so that they cut a jagged edge. I guess the cloth edges would not unravel because there is no thread that is always near the edge to pull away.
Sorry but don’t have an answer directly on point.
That saw tooth pattern that haj describes is also found on the edge of the petals of carnations, which is why those flowers were called “pinks” for many years.
[sub]phew. It’s taken me YEARS to work that useless information into a conversation. [/sub]
So my guess is that there wasn’t so much a past-time called pinking as there were shears that did pinking for you.
Redboss
You should have kept quet and nobody would have 
There was a thread on this very topic about a year back but guess what, the search function is $&!#.
What Redboss said just about covers it IIRC.