"You know what," the barbarian said after a moment, "I think he's mine." She slammed her mug on the table and stood up. You gulped audibly; you'd always been a rather short, scrawny type and she was tall for a woman - or, well, for anybody - and overtopped you by almost a head and her form rippled with muscle. Still she was quite lovely, you had to admit, with wavy brown hair to her mid back, and her large, shapely breasts and hips were fully on display, and between her legs - you couldn't help but blush furiously at the thought, and you could feel your manhood stiffening.
"Aww, look at that, he's cute," the barbarian said, seeming to notice your blush. While the two demons were furiously making out behind you, she grabbed your arm and hauled you over to her table, then placed a hand behind your head and shoved it forward onto her breast. Instinctively your lips found her nipple and began to suck.
At once a feeling like an electric shock raced through your body, and as you sucked you could feel yourself starting to change. You were growing, adding several inches to your height and muscles were cording your frame; you could feel your clothes rip and fall away, leaving you nude. Your ass swelled as your waist narrowed, leaving you with a shapely but athletic frame; your legs grew long and sleek and strong, a warrior's legs. Your hair suddenly tumbled past your shoulders, a thick mane that had become bright red, and you could feel your face reshaping, becoming feminine but strong. Your nipples hardened, standing firm from your chest, and then a pair of breasts exploded behind them, becoming at least as large and firm as your partner's, you realized with pride. Then, if your mouth hadn't already been full you would have gasped as her hand found its way between your legs, fondling your rock-hard junk - and then suddenly she shoved, hard, and you could feel it retreating inside you, leaving a warm, moist opening behind. The sensation as your partner's fingers slipped inside you was like nothing you'd ever felt before and you groaned deep in your throat.
You pulled away from your partner's nipple and gave voice to your pleasurable moan, your voice deep but unmistakably feminine. Where once had been a scrawny male thief now stood a strong barbarian shieldmaiden. Power raced through your form, lust for battle, for drink - and for sex. You couldn't remember why you'd feared the transformation; this body was so much better, stronger, more desirable than your old one.
You met your partner's eyes and grinned fiercely, then planted a firm kiss on her lips and forced her back so she fell onto the table with you on top of her. She was still working your slit and your fingers found hers to return the favor. The other women in the bar stepped back from the table and cheered, but you didn't care that they were watching anymore. You had a feeling that this sex might get a bit rough before you were done, but that was okay. You didn't mind showing off your new body, and you had a feeling that the person you'd become liked it rough.