The court heard Davies had been in a relationship with Mr Coghill for nearly four months after they met through a lonely hearts advertisement in a local newspaper.
They were celebrating Mr Coghill’s 45th birthday on October 10 last year with a meal and drinks in his Newcastle bedsit.
The court heard how they had gone to a local supermarket, buying two bottles of vodka and food for the evening, before going to a pub together.
They later returned to Mr Coghill’s home, but as the evening progressed, Davies grew upset because she wanted to have a baby but was not pregnant.
As Mr Coghill moved to comfort her, she asked him to kiss her with his tongue, and when he did so, she bit it off.
“He sat and comforted her, that comforting moved on and it became amorous, he was cuddling and kissing her,” Julian Smith, prosecuting, told the jury.
“She told him she loved him, she asked him to kiss her using his tongue. He did so and within a few seconds, she bit down hard on his tongue.
“Obviously this caused him pain, he pulled back, and the tongue had come clean off in her mouth. “She had the piece of tongue in her mouth, he saw her take it from her mouth, and it fell to the floor.”
Mr Coghill went to rest while the pain subsided, and eventually fell asleep, but was woken by Davies biting his elbow, Mr Smith told the court.
He said Mr Coghill pushed her away, and she decided to call an ambulance to the flat, who in turn alerted the police.
Upon their arrival, they were greeted by Davies holding the remains of Mr Coghill’s tongue in a plastic bag, the court was told.
“Later, Tracy Davies called the ambulance service,” Mr Smith said. “As a result of that call the police were also called.
“They arrived at approximately 4.36am. The door was answered by Tracy Davies. She was holding a small bag with a lump of flesh in it.
“She told police, ‘We have had a domestic. I have bitten his tongue off. Here it is’.” He added that Davies was surprised when police arrested her moments later, telling officers: “You’re joking!”
Mr Coghill was treated at the accident and emergency unit at Newcastle’s General hospital, but surgeon’s decided the risk of infection was too high to consider reattaching the torn tongue.
Davies, 40, of Sunderland Road, Gateshead, denies one count of causing grievous bodily harm with intent.
The case continues.