Exploring desperation and pushing a lady to her limits is what does it for me. My ideal fantasy is pretty well-honed...
It starts with an afternoon at my local pub (does it have to be mine? Yes - you'll see why). We have a few drinks - it's important to onboard some liquids or this wouldn't work! Enough to loosen her inhibitions, but not so much that she's drunk or out of control. This is a consensual fantasy (I do have non-consensual ones but they're pretty difficult to plan!), so she's agreed not to visit the toilet. We've agreed a signal for when she wants to leave: when her bladder is starting to strain but she's not fully desperate.
My house is about half a mile away down a dead-straight road. Close enough that she can make it there, far enough that she's going to become a little uncomfortable. We set off hand-in-hand, but my hand soon strays to her butt, feeling her muscles clench occasionally, gauging how long she can hold on for. Perhaps she's also a little aroused by a bursting need to pee (I believe a lot of women are, although they don't often admit it), so she's a little flushed, wanting to let go but also enjoying the sensation sufficiently NOT to want to let go. As we walk, she talks, perhaps mutters about how much she needs to pee. Perhaps she hints about dropping her knickers and going: there's not much cover here so that would be a brave and sexy act in itself. But that's a fantasy for another day: I've no wish for her to be mortified by passing dog-walkers or traffic. Perhaps I need to encourage her to hold on. Perhaps I loosen her belt for her or - if it's quiet - slip a hand inside her knickers and hold her briefly. Reassuring, not forcefully. The goal is to get her home, dry: I'm not really aroused by wetting.
Fifteen minutes or so after leaving the pub we get to my front gate. Why does it have to be my house? Because my garden is completely enclosed and private. I do have exhibitionist fantasies, but today is purely for my eyes. She's in a pretty agitated state by the time we get back, tugging at her waistband, perhaps clutching herself. She's given up any pretence of dignity and purely focussed on containing herself. Once she realises we're isolated, it's all I can do to persuade her not to squat down right there and then. Because I've got a treat planned for her as well as me. In the middle of the lawn, there's a blanket and a nest of cushions laid out. She doesn't need any encouragement to collapse on them, and sighs with relief as I slide off her knickers and part her thighs. Somehow, she convinces herself not to pee right there and then.
I go down on her, fully aware of trembling thighs, clenched buttocks and vaginal muscles. This is heaven for me right there and then. How long will it last? As long as necessary. We both know that pee will happen - it's only a question of time...