Ideas
+53
Cock Fucking
Not sure if this has already been suggested.
If a test subject has a huge cock, it'd be hot to be able to fuck it. Put your dick in their urethra and fuck it.
Not only that, but if their cock is smaller than yours, you can envelop their cock with yours, kinda like a fleshlight.
Customer support service by UserEcho
From a quick look there are other topics for sounding and sheathe play but none explictly for cock fucking, thats only been a suggestion in the comments of said posts. It also says on fek's website that sounding will be in the game but doesn't specify if cock fucking as a part of it.
As an extra suggestion, if cock fucking does get added I would really like to see testicle inflation in proportion to the size of the balls of whoever cums. Could even assign an individual subject to be inflated with cum from other subjects/staff and when they get milked, they can have a multiplier related to how much semen their balls have been inflated with which will apply to any of the 6 chemicals you're harvesting from them, along with the subjects testicles retaining some of their enlarged size after they are milked.