I wish I could be kneeling between your legs with your cock idly held in my mouth, while you slowly fill me with urine, never letting me know when you're going to start emptying down my throat next
Rocking back and forth every once in a while to catch some friction on your tongue, cock twitching after releasing my piss on it, grabbing your head when I start speeding up into fucking (and cumming down) your throat, throbbing after using you, pissing again after a few minutes...
Though I also greatly enjoy the idea of just urinating in your mouth with a semi. Not giving you any heads-up, no, just trickling onto your tongue, forcing its way into your throat with the pungent taste and smell you can't ignore.
At first, when you place my tip between your lips, you think I'll let go immediately. But nothing for at least a couple minutes, maybe even an hour, while I'm at my desk working. It's like I've forgotten you're even there.
Somewhere during that time you've idly started sucking me deeper, entire head in your mouth. You're distracted enough to give my cock a little lick here and there, but you're not bobbing your head up and down, stroking me, sucking on my balls, or any of the bells and whistles. Just sucking very gently. Lost in your cock-drunk mind.
Until suddenly, without a warning, without any movement from my cock, it hits your senses. Strong. Bitter.
You're shocked, having forgotten by now that I was supposed to be peeing in you. But as my hard stream shoots into your mouth, you have to focus hard on swallowing. You drink enough to catch your breath and pull your throat down over my cock, and my stream quivers to the feeling of emptying my bladder into your esophagus.
You're fine holding your breath, but my piss keeps flowing. And flowing. And flowing. You start to worry if you can keep up and be my idle cocksucking urinal.
My stream stops right there. I shoot another spurt of urine. And another. And another. And another after that. Between one of the spurts, you managed to pull me out of your throat and catch your breath without choking on my piss. I force some more piss out...
...but you, being the excellent urinal you are, suck the rest out of my cock directly, so I don't even have to force it.
Now you've gotten a good idea about what your role entails.