The Thanksgiving Holiday is always the fourth Thursday of November and many companies close their offices for the next day as lots of people travel to be with relatives on Thanksgiving.
For many people and stores the Christmas Shopping Season "officially" is considered to start on Thanksgiving Day.
Combining that many people have off from their regular jobs, and the "shopping season" has just started, many large stores have very deeply discounted, loss-leader type merchandise on sale that day (usually only for a few hours in the morning) to attract people to the store and get them in a buying mood.
The way most people act, if it were in the UK the local Constabulary would start reading the Riot Act. It is definitely not for either the faint of heart or frail of body