Set the night after Elizabeth and Jack's Curiosity scene in 'Dead Man's Chest'.

Elizabeth stepped up onto the deck. There was no one there apart from Captain Jack Sparrow, who stood with his back to her, one hand resting on the wheel, his eyes lost somewhere on the horizon. He turned as she walked up the steps towards him, her hair blowing in the slight night-time breeze. She approached Jack cautiously. He turned back around so he was facing away from her, avoiding her seeing the grin that had spread across his face.
"Miss swan," He said, trying to sound surprised, "What brings you out here at this time of night?"
Elizabeth looked down at the floor, then back up at the pirate,
"Curiosity." She replied as coolly as possible, even though her heart was racing. Jacks grin grew. He spun around to face her.
The two stared at each other for a moment, Jack smirked as he took a step closer towards her.
"And what would madam be curious about?" He almost whispered in a gruff voice. Their bodies were inches apart.
Elizabeth looked Jack dead in the eye, there was a wild glint in hers that Jack had never seen before. This aroused him greatly, Elizabeth's eyes scanned Jack and she noticed his growing erection. She moved her lips next to his ear and whispered, "I want to know..." She paused slightly, mustering up all her courage, "what it tastes like."
Jack's eyes grew wide with surprise at the forwardness of what she had just said. Not wanting her to go back on this offer (something that he had been waiting for since he first met the young woman), he tangled his hand in the back of her hair and pulled her up into a rough yet passionate kiss.
Elizabeth squealed and flinched slightly at the abruptness of the Captain however she quickly relaxed into the surprisingly good kiss. Their tongues met and flicked across each others' hurriedly, each exploring the others mouth with haste because they had both been longing for it for ages.
Elizabeth gasped as Jacks hand found itself upon her breast; he squeezed it, not too hard but firmly enough to get the response he wanted from Miss Swan. Elizabeth took a deep breath 'it's now or never' she thought to herself as she rubbed her hand up Jack's inner thigh. He opened his dark, wild eyes as her hand crept gently over his stiffening member.
Before he knew it his trousers were down around his ankles, exposing himself fully to the bare ocean breeze. Elizabeth's soft hand was stroking him gently. Highly aroused, he ripped open the front of her dress to expose her pert breasts. She broke their passionate kiss by gasping as his thumb rubber over her hard nipple. Jack grinned, she look exactly as he'd imagined on many a lonely night.
Elizabeth winked at Jack as she sunk down onto her knees. Jack's heart thudded as she took him in her mouth and began to gentle suck. "Eliz...a...beth" he groaned. She was surprised at how much she enjoyed it. Jack felt something build up in the pit of his stomach, 'oh no...not yet...hold it' he thought – he really wanted this to last as long as possible.
He gently lay Elizabeth down on her back and gently removed what remained of her dress and underwear, as well as his own apparel. She shuddered in the cool breeze of the early hours. Jack kissed her slowly, less forcefully but just as passionately as before. He was met with Elizabeth's keen response. He then kissed down her neck, took his time over her breasts and down her stomach. Elizabeth watched contently as he worked his way down her naked body. She wanted this moment to last for ever. He kissed her inner thighs, occasionally teasing her by blowing gently past her wet pussy, she was really craving him. When she couldn't take the torture anymore he finally gave her what she wanted; he flicked his tongue quickly across her clitoris – making her arch her back with pleasure. She had never felt anything like this before. Yet she wanted more.
"Captain..." she gasped after a few moments, "I...need you...inside me.." Jack grinned up at her from between her legs.
"I love the Captain thing darling, but considering our situation I suggest you call me Jack" He growled provocatively, winking at the beautiful naked women before him – this was definitely a sight he would remember forever. He climbed slowly on top of her, positioning himself at her opening. He looked at her for a nod of approval, she gave it.
He gently pushed himself inside her. She was so wonderfully tight and warm and wet. He shut his eyes, trying to regain control over himself. Meanwhile Elizabeth was fighting the urge to scream out with pleasure – she couldn't risk even Cotton's parrot stirring. Jack then gently started to thrust into her, "oh...Jack" Elizabeth panted. She could feel something stirring inside her that she had never experienced before. They moaned together as the pace and force quickened.
"You...have no idea...how long...I've wanted...this" Grunted Jack. Elizabeth grinned and blushed, "Me...too.." was all she could manage back. The pleasure they were both feeling intensified, they lost themselves completely in it. Elizabeth threw her head back as the euphoric waves came over her, while Jack closed his eyes and clenched his teeth as he came inside of her. His arms shook as he lay himself down on her chest, they were both gasping for breath.
When he could muster it he looked up at her beautiful, exhausted face. They held each others' gaze for what felt like forever, saying everything with their eyes. The sun was rising now, Jack knew the crew would all be up soon. He sighed deeply, without a word he gathered his clothes and left her.
Elizabeth sat biting her lip, deep in guilt, but not regretting what had happened.