Neil Harris let rip at his players after Millwall were crushed 5-1 by Peterborough.
The Millwall manager pulled no punches after watching his side slump to their first defeat the season following a scintillating performance from Grant McCann's hosts.
First-half goals from Marcus Maddison, Paul Taylor and Gwion Edwards had the Lions floundering.
A second strike from Edwards and a close-range Tom Nichols finish delivered the knockout blows before Steve Morison hit a late reply for the visitors.
Harris was brutally honest with his assessment of Millwall's no-show at the ABAX Stadium.
He said: "I'm absolutely gutted, to be honest.
"Disappointed, frustrated, angry, embarrassed are probably good words to sum that up.
"People can make mistakes and we can have a bad night, but if nine players have a bad night, then you are going to get spanked.
"That was a harsh lesson for some of my young players tonight. It hurts me and it will hurt a lot of my players in the dressing room.
"We had problems we could cause them but it just didn't materialise. Defensively we were all over the shop, not just the back four but the midfielders as well. It seemed as if everyone forgot what their responsibilities were.
"That's my biggest gripe is that, under pressure and on a bad night, some of my players couldn't do the basics. It upsets me.
"My players were c***."
Maddison's sixth-minute opener had an element of fortune as his cross from the right touchline evaded the Lions defenders and sailed into the net.
Yet Taylor's finish, just 90 seconds later, was more emphatic as he drilled a low shot past Jordan Archer after good work from strike partner Nichols.
Nichols' deft chip allowed Edwards to head past Archer on 20 minutes and the same pair combined to put the game to bed on 52 minutes as Edwards tucked away Nichols' cross.
Former Exeter striker Nichols got his reward for three assists when he slotted in the rebound after Archer failed to hold Jermaine Anderson's shot before Morison grabbed a late goal for the visitors, yet it was hardly any consolation.
Fledgling Peterborough boss McCann's managerial career has not even stretched into double figures yet and the Northern Irishman beamed: "I thought we were excellent from minute one.
"Even from the kick-off we wanted to get at them. I was really pleased as, to a man, we were superb tonight.
"I thought we showed a good tempo all night and we showed Millwall that we wanted to get after them.
"We knew they would hit balls into [Steve] Morison and we stopped them doing that.
"Millwall have got so much energy and we knew we had to match that. I think we matched it and went beyond it.
"We stretched the game really well tonight and defensively we were excellent.
"We conceded a sloppy goal at the end, which was disappointing to lose, but I can't complain as we've scored five excellent goals and thoroughly deserved our victory."