Cambridge director of rugby Bob Crooks has expressed his anger with his side's performance in Saturday's National One defeat by Tynedale.
A last-minute Allen Rogers try cost Crooks' men in the 37-32 loss at West Renault Park.
The result brought to an end a three-game winning run for Cambridge.
"We had a moronic attitude towards possession, we must have given away 20 sets of possession," Crooks told BBC Radio Cambridgeshire.
"We've got our full-back throwing the ball to blue and white shirts.
"With due respect to under-8s, it's under under-8s stuff."
Cambridge still sit third in National One after a campaign dogged by financial uncertainty and injury concerns.
And Crooks has warned his men they could tarnish all their good work with a sloppy finish to the season.
"They get enough done for them so they need to change their attitude," he said.
"They need to be a little bit tougher and a bit more physical for next week, otherwise what will be perceived as a really successful season will be clouded by the end of the season."