Jack Tweed denies carrying out the attack
Jack Tweed has told a jury trying him for rape he had no idea a friend was in the room watching, until he joined in having sex with the same woman.
Anthony Davis knelt on the bed and joined in the sexual act, he told Snaresbrook Crown Court.
Mr Tweed, 22, the widower of Big Brother star Jade Goody, and Mr Davis, 26, both deny raping the woman.
The alleged rape happened at Mr Tweed's Essex home in Brandesbury Square, Woodford Green, on 4 September 2009.
The victim said she was "horrified" and went into "complete lockdown" when Mr Davis joined Mr Tweed on the bed and they both "raped her together".
Club promoter Mr Tweed told the court the first he knew his friend was present in the room was when Mr Davis had knelt on the bed.
Mr Tweed said sex with the teenager had been consensual.
"She was flirty towards me and very friendly," he said.
The teenager asked for a pair of socks or tracksuit bottoms to keep warm, he said.
"I just said, 'go and look for them', and she said, 'come and help me look'.
"I turned round and (she) was standing right behind me."
He told the court they then went into a bedroom.
"We looked at each other and just started kissing. We made eye contact," he said.
"I may have made the first move. She was kissing me back and had her arms round me."
Under cross-examination by Linda Strudwick, for the prosecution, Mr Tweed denied using the 20-year-old student from Hertfordshire, "like a sex object".
He also denied targeting "the shyest, prettiest girl "and getting her in to a darkened room together with Mr Davis in an "agreed plan" for sex.
"I didn't know he was there until he got on the bed," Mr Tweed said.
Asked repeatedly if he would have found it "creepy" or odd if he had known Mr Davis was watching him have sex with the woman, Mr Tweed insisted he would not have been angry.
"It's not something I would do," he said.
Judge David Radford asked Mr Tweed if he said to Mr Davis "What the hell are you doing?" or anything like that when he became aware of his presence and he said: "No."
The jury has heard the woman, now aged 20, went with her friends to Mr Tweed's house after a night out at the Embassy Club in Mayfair.
Her first contact with Mr Tweed was when he started kissing the back of her neck while wearing boxer shorts and a long dressing gown, she said.
She initially tried to laugh it off but he soon became "more heavy-handed", she said.
The situation changed when Mr Davis stood inside the bedroom and told Mr Tweed: "Don't worry Jack, I've got the door, do what you've got to do."
She said Mr Tweed raped her by the windowsill and, as she tried to escape, pushed her on to the bed.
Mr Tweed then raped her again, with Mr Davis orally raping her at the same time, the court heard.
Mr Tweed, who married Big Brother star Goody shortly before she lost her battle against cervical cancer in March 2009, and estate agent Mr Davis, of Stradbroke Drive, Chigwell, Essex, are both on bail.
The trial was adjourned until Thursday.