Condoms are a turn-off and the sight of them can make boys lose their erection, according to teenage girls.
The teenagers, interviewed for research into condom use among young people, give graphic descriptions of their reasons for disliking condoms.
Nicola, who like the rest of the teenagers does not give her surname, said:
"My ex told me he never used condoms - just the sight of them he said made him lose the stiffy. He had an almost phobia about them."
Jane echoed this. "His penis doesn't really like condoms. It makes him soft."
The interviews were compiled by Lynda Measor, of Brighton university, who presented her findings to the conference.
She trained teenagers to interview young people on her behalf, believing they would be more willing to confide in their peers. Focus groups were held in English schools and with teenage mothers.
In many cases, the most revealing information about boys' attitudes came from their girlfriends. Lauren quoted her boyfriend as saying: "Enough girl with the condom thing!... Using one means it's fucking and not making love."
Other interviewees claimed that their boyfriends blamed condoms for any difficulties in achieving and maintaining an erection. Julie said: "He had been losing the erection all through foreplay, and after we'd had sex he made some comment about sodding condoms."
Dr Measor found that in many cases, it was the girl who agreed to forget the condom, rescuing the boy from his performance difficulties, but at the same time putting themselves at risk.