Prison bosses are urgently investigating this footage of prisoners throwing parties, and apparently drinking booze and taking drugs - all while behind bars.
The outrageous clips were recorded on a mobile phone apparently smuggled into category C HMP The Mount in Hertfordshire on a number of occasions over the last month.
A dozen lags can be seen lining the corridor outside their cells dancing to blaring loud music, apparently completely unsupervised by guards.
Two burly prisoners have a 'dance off' before one shouts "dance party" and another tattooed inmate strips off and shimmies towards the camera.
Another video shows around six rowdy men crowded in a cell passing around a suspicious substance in a home-made bong with one boasting to the camera: "Get the merchandise on the tele."
Two men can be seen smoking the smoke-filled bong, with one taking a swig from another bottle filled with a yellow liquid.
One additional video shows one lag giving a guided tour of his packed cell and four phones.
As a pot of blue pills is filmed, a prisoner boasts: "Yes, we have the f***ing steroids, my friend."
His cell mate can also be seen brazenly chatting on his bed on another phone while holding a screwdriver inside the cell which is packed with food and soft drinks.
A Prison Service spokesperson said the men in the videos have been stripped of their privileges.
He said: "We are urgently looking into this video and have already placed those who we have identified as being involved on report."
"They will also be stripped of their privileges and referred to the police for further investigation.
"We have a zero tolerance approach to banned substances in our prisons. Anyone who has broken the rules will be stripped of their privileges and faces having time added to their sentence.
"If there have been any failures in the supervision of prisoners, appropriate disciplinary action will be taken."