there will be candidiasis (thrush) if the immune system is not stable and cannot cope with bacteria of another biotope (feces). so no good, I don't recommend it.
Nothing will happen. The maximum is warm (if the shit is fresh and warm).
But seriously, there is nothing dangerous in the feces (if we are talking about a healthy person). Stool is 75% water and 25% solids. Simply put, it is oily processed by your own body.
When I just started discovering the world (of other men), just kidding (no). The world of the Internet, I talked on the forum of very strange people (jerking off from parks, lovers of sticking carp in the mouth, etc.) I came across one woman who liked to smear herself with feces (of her own production), self-satisfied with her hand. At the end of all her fascinating things, she just washed and doused herself (washing the vagina with solutions of medicines). Baba is alive and well. So everything will be ok.