Semen ejaculation could be forced either by electroejaculation without causing an erection or by injection of a chemical that forces an ejaculation with minimal erection. Both procedures are realistic and done in stock animals.

The subject would be out of control and could react in different ways, from excited to nearly panicing from their body building up a chemical induced ejaculation or semen being electrically forced out without any further interaction (or way to prevent it for the subject). This could easily tie into more heavy bdsm/submission desires of a subject.

It would fit a lab environment very well and cater to all ways of speaking to the subject, too. Different lab equipment would  be needed to be crafted for this, from chemical substances to electrical probes (including electrical sounding tubes that can be inserted into the penis while the tube won't block semen flow).

While looking through the suggestions I did not find the specific suggestion of flacid ejaculations, so I wanted to add this here.

There should be an option so a character's penis can be uncut. Also, any kind of foreskin play would be great ie. tugging, pulling, fingering etc.

the idea is a cross between regular oviposition, and my sperm replacement idea, the idea is that a monster(whether you develop the creature, it's a previously undiscovered species of mollusk, insect, etc, or it's an alien)the creature will come up to a male subject, extend and insert it's ovipositor through the penis, coating the entire ejaculatory duct with fluid that alters the composition of the flesh to make it stretchy , and into the testes, where it pumps the same fluid into the organs that alters composition(to make the testicles stretchy)included with the fluid is a bacteria the binds itself to the host spermatogonia(thats what make the sperm)and in short swaps out the hosts genetic information with whatever genetic information this creature happens to carry, after that, the creature will draw eggs(either the size of pollen of the size of chicken eggs)into the hosts drastically altered seminiferous tubules where the eggs can be fertilized and later be ejaculated out(or pushed out in chicken egg sized lumps)

The option to have some more capabilities for cbt or ballbusting, ranging from incredibly mild like light taps to the balls or ranging through to more extreme things for those that are into that

Urethral sounds, penis plugs, catheter tubes.

both can be for male or female, but male is more common

The idea of feeding a subject their own cum every time they orgasm, such as a milker with a tube connected to a gag in the mouth of a subject.

The chairs should lower to or near the floor when during self pleasure.

For 2 reasons;

1. So that the subject can see what you're doing, though this is superficial until voyeurism is coded.
2. And right now, the only way to gave a subject a facial is to ride their dick while you have a dick of your own that's been customized to not veer off and point in the wrong direction.

Not just having sex with underwear still on, but also using them as a sex toy or bondage/chastity item. Dry humping/grinding, using them as a gag, edging the subject and then making them cream their skivvies, face sitting while wearing underwear, etc.Maybe have a serum that makes subjects react negatively or positively to certain underwear colors. For example red/purple/blue/black undes would make the subject more aroused, but brown/white/grey/biege underwear would make them lose arousal and so on.

Briefs
Boxer-Briefs

Boxers

Trunks

Jockstraps

Speedos

Thongs

G-Strings

Panties

Add the ability to adjust the rack, or purchase different racks to force various compromising poses and easy access to the subject's various part - FOR SCIENCE!

visible shaking and pounding of chest when heart is beating hard or fast.