There isn't enough triple-anal penetration out there.

Seriously, the sight of an asshole being stretched to its limit as a trio of fat cocks all pound into it from various angles is very delightful for an anal fiend such as myself. Even rarer is a quad-anal dicking.

Just cram as many dicks as possible inside someone's tight ass and watch it stretch in desperation to accommodate everyone, each dick thrusting at its own pace as everyone shares the same hole, before leaving it a messy, gaping mess.

Now THAT 👏 IS 👏 WHAT 👏 I'M 👏 TALKING 👏 ABOUT!

I'm also definitely a fan of extreme/multi insertions, so I hope my project doesn't disappoint. ❤️

Overproduction; Either a pair of boobs or testes or whatevs, that produces so much excess milk/cum/eggs/fluid that they steadily engorge over a day, hours or just minutes, and they need to be drained regularly to avoid discomfort and injury~

Pulsating: Pretty self explanatory, though applied to a bit wider range, like boobs, hyper bits, a gravid belly or a overly muscled frame~

Sentient bits: You already know this one of mine. A body part gains sentience and expresses its own motives, desires and personality, whether simple or intricate, and could autonomously move on its own to varying degrees~

Horror pregnancy: Think Raccoonshinobi. After getting knocked up by monstrously virile bulls like Tak, the resulting gestation happens alarmingly rapidly. The young grows to full term in a matter of minutes or seconds, accompanied by a lot of painful unborn kicking and thrashing. Belly bursting's a big bonus, but not mandatory~

Weaponized milk: This only applies to a few of my girls like Soma, Lenneth and Callie. Girls like them could control the properties of the fluids their breasts produce and fire them out semi-at will. Need to detain a bad guy? Churn a batch of protein-rich milk that hardens in contact with air and hose them with the stuff. Locked iron door? Turn your boobs into hugh-pressure water cutters. Injured after a gunfight, self-suckle some healing milk and watch those wounds close back up in seconds~

Overproduction and pulsating bits is definitely something I'm into, weaponized milk can be fun, with sentient bits and horror pregnancy both being pretty neat even if they're not my usual go-to! Hyper/rapid pregnancy is definitely best when it's just eggs, for me. ^^

most of mine involve growth of some form or another, hyper/muscle/macro/multi etc.
But like...I do really go in for the idea of combining these with a form of hyper overproduction that causes the body to mutate/transform in horny ways, changing the subject to fit their growing desires.
Like say making out with an already huge fur who seems really, really into kissing and the more you make out the larger, more plush their lips become, but it's not enough to satisfy them, then abruptly you're being smooched from more angles than the one and you find they now have three identical heads all trying to get in on you. Or they've abruptly got an extra set of beefy arms to better hold you in place. Or extra hyper appendages that exist to drench you (and the room/neighbourhood/city/countryside) outside even as they stretch out and fill your insides with the original.
Add on to those concepts with corruptive/mutagenic fluids that make those exposed begin to transform/mutate to adapt to, or better suit those (or even their own) desires for more and more.

Same here! Hyper excessive growth and production is pretty much my go-to - especially considering big furs with big bits is already hot; big furs getting even BIGGER and making an even BIGGER amount of a mess thanks to their equally-growing bits is even HOTTER~ ❤️‍🔥

Personally my favourite combination is that, plus unintentional destruction/property damage. Even better when the hyperfur is all blushing and panicking and desperately trying to hold back as the impetus for the transformation (either an enabler friend of theirs or a chemical accident/experiment/magic/etc) causes them to massively overproduce despite panicking and trying to hold back (which typically just makes it worse as they go from merely gushing precum to outright firehosing the spoo outwards because they thought they had it under control but were just getting severely backed-up and a lapse in concentration undoes all their carefully self-imposed restraints~) ☺️

hell yeah, that's great stuff, or overloading compression wear that was designed to contain them, but was never made to account for just how big and productive they become over time