Hmm, where to begin...
It's been quite a fantasy of mine for some time for my girlfriend to defecate into my mouth. But just a plain shit would be boring so we'd have to liven it up. We'd start in the "69" position and she'd be slobbering all over my cock using without her hands and I'd be licking her general cunt area. I'd wet her bum and anus with my tongue for a bit then begin by sticking a finger in her there and then swirling it round for a bit. I'd then stick a bigger finger (say my little finger at first followed by my forefinger) and get a bit of shit on it and have a taste. Then she'd stop sucking my cock and sit up so her anus is better aimed at my mouth yet she'd still be able to toss me off. Then she'd try to shit. Of course it's near impossible to shit without going for a piss so I'd get a bit on my chest, with a little gathering in the makeshift pool that is the little dent where your chest and throat meet. The rest I'd try to lap up with my tongue. Then the anus would open only to be probed by my tongue again but this time deep, deep into it. I can imagine her complaining that my stubble is rubbing on her bum it'd be that deep into her. The love dough would come out and I'd open my mouth nice and wide and try to get it in, in one whole erotic elongated lump. It'd probably make me choke and activate my gag reflex but that's more of the fun as opposed to a downside. Then when the initial big piece is in my mouth and sticking out the top (I wouldn't let her shit for at least 3 days before we do it) I'd make her do the more liquidy shit as she rubs her bum over my face so it's smeared all over me. Then I'd take a photo.
Another time (hell, we could even combine it!) I would like to sit in the bath with her. After the shitting exercise I could make her kneel down and then crap on the top of her head but towards the front so it awkwardly and annoyingly slides down her face but I won't allow her to touch it to move it away from her eyes, nose or mouth. After about five minutes of that I'd begin to piss on her face. I'd use a block of wood to keep her mouth open and force her to swallow it. Then I'd punch her.
I wish I could do her up the arse a few hours after giving her constipation tablets so rectum is simply chockerblock with liquidy stool and about to burst into a sort of TNT diarrhea explosion. I'd pound and pound (on GHB or something so I can last for years) and then when I'm about to cum I would spin her around and slam my cock right into her throat. She'd gag from both the taste and the fact that there'd be my cock in the back of her throat but any vomit that tried to surface would simply be blocked by my meat. I'd cum so hard in her throat that it'll hurt and if it didn't then I'll kick her!
