I was designing some new units, when i clicked on one of those blue snake things by mistake (Ophidians). I'd recently gained the option of recruiting them after my influence spread over one of their lairs. (BTW, there's no icon on the 3D map for the lair, it's just empty terrain.)

It brought me to the page where you add equipment and such, and it let me add things to the snake as if it were a person. Most (but not all!) of the armor and items didn't work, until I changed the gender. The model turned into a female human, and I was then able to add everything a normal soldier could use (helmet, horse, weapon, etc.) When i switched the gender back, it was now a male human model. All the buffs from the equipment were adding to the snake's stats.

It even let me build it. The cost switched over to straight labor and whatever the equipment cost, no diplomacy points or food. So now I have human soldiers with all the base stats AND perks of the Ophidian. They're immune to magic and have a snakebite attack! I haven't used them in combat yet, so I'm not sure what happens.

I named him Snakeman.  

As funny as I found it, that leaves room for some serious abuse.