The winning passage reads:
"And he came hard in her mouth and his dick jumped around and rattled on her teeth and he blacked out and she took his dick out of her mouth and lifted herself from his face and whipped the pillow away and he gasped and glugged at the air, and he came again so hard that his dick wrenched out of her hand and a shot of it hit him straight in the eye and stung like nothing he'd ever had in there, and he yelled with the pain, but the yell could have been anything, and as she grabbed at his dick, which was leaping around like a shower dropped in an empty bath, she scratched his back deeply with the nails of both hands and he shot three more times, in thick stripes on her chest. Like Zorro."
The passage is from Giles Coren's book "Winkler".
For more, read Giles Coren wins 'Bad Sex in Fiction' award.