Snub: a refusal to recognize someone you know
Nothing feels quite as bad as getting the cold shoulder from someone you love, especially if that someone is your Dad...why wouldn't he just play catch with me? Anyway, ignoring a friend is nothing new and neither is this phrase which has its roots in jolly old England at about the time Willy Shakes was writing his plays.
Back in those days it was common to have visitors and travellers drop in unannounced. Hotels didn't really exist yet and your best bet for finding a bed was to just knock on someone's door. Now, if someone agreed to let you in they were also obligated to feed you, which is a great custom. Most visitors got good hearty food but if someone came in who was a persona non grata
he would be given the less than desirable cut of meat: the cold shoulder of beef.
The phrase stuck and travelled the time highway all the way to us. It was the best our ancestors knew how to insult someone; they didn't have "Yo Mama" back then.
Now imagine eating it cold...