A vulnerable man was threatened with castration if he told the police about being beaten up and robbed.
The 29-year-old was "petrified" during the ordeal, during which he was knocked to the ground and punched.
Two of the robbers were given lengthy prison sentences at Leicester Crown Court. A third has escaped detection.
Wayne Hardy (41), of Grange Court, Loughborough, was jailed for seven years and 10 months. His girlfriend, Robyn Rebecca Driscoll (37), of Oxford Street, Loughborough, was given a sentence of six years and eight months.
Hardy and Driscoll admitted robbing the victim of £280 on December 8.
Judge Simon Hammond said: "This was a very nasty robbery, involving a vulnerable man in his own flat late at night.
"Violence was used upon him and there were elements of cruelty. You were pitiless and he was threatened with castration if he told the police."
Neil Bannister, prosecuting, said Driscoll knew the victim, and was aware he collected large amounts of change.
Driscoll, Hardy and the unknown male were captured on CCTV at 12.30am in Loughborough town centre approaching the victim's flat.
Mr Bannister said Driscoll went ahead to approach the victim, saying her mother had collected some change for him.
She went into the victim's flat, and asked to use his toilet.
She asked, because her hands were cold, if he could undo the top button of her trousers.
When she came out of the toilet she called to the two accomplices, waiting in a rear yard.
Driscoll said: "Do what they say or they'll hurt you."
Mr Bannister said the first man began demanding coins and when the victim tried to make a run for it, the man grabbed him, threw him on the ground and punched him.
Driscoll told the first man the victim had tried to touch her sexually and he threatened to stab the householder.
Mr Bannister said: "It terrified him. He tried to escape, but was dragged back.
"He says it felt like both men were hitting him. The first man threatened if he told anyone he would come back and cut his b**** off."
Driscoll told him if he said anything she would make an allegation of sexual assault and pointed out she had his fingerprint on her trouser button.
The victim suffered a black eye, an open wound above one eye and a lump on his head.
On the afternoon after the raid, off-duty police noticed two people at a supermarket putting a large quantity of coins into a change conversion machine.
The officers questioned the pair, which led to the two defendants being arrested.
In mitigation, the court heard both defendants had been misusing drugs, regretted their actions and had written letters of apology to the victim.
Driscoll was said to have been suffering from a mental health relapse at the time.
Christopher Brewin, for Driscoll, said: "She's disgusted about what happened."
Jonathan Straw, for Hardy, said: "He maintains it was the other man who used the violence towards the victim."
