Newcastle, who will face Liverpool on Sunday, lost to Leicester City and Crystal Palace in their last two Premier League games.
Newcastle have lost their last two league games after starting the month of November with a narrow 1-0 victory over Bournemouth away from home at the Vitality Stadium.
The Magpies suffered an embarrassing 3-0 defeat to Leicester City at St. James’ Park after the international break.
Then last weekend, Steve McClaren’s side were humiliated 5-1 by Crystal Palace at Selhurst Park in London.
Newcastle legend Shearer was far from impressed with the performances of the team.
“The performances have been hopeless, embarrassing, and there has been a lack of commitment and effort,” the former England international striker has written on Coral.co.uk.
“They won’t get away with that against Liverpool. Things have to improve. It’s ok getting beat because everyone gets beaten but their last two performances have been unacceptable.
“If that happens again on Sunday, then no doubt the fans will let the players and the manager know what they think.”
Newcastle will take on Liverpool at St. James’ Park in the Premier League on Sunday evening.
Despite being the home team, the Magpies will head into the encounter as underdogs.
Liverpool are on a good run of form and the players are playing with confidence.
It will be tough for Newcastle to win against the Reds, and they will need to score an early goal or at least not concede in the first half in order to stand a chance of picking up all three points.