In fantasy, I like the concept of humiliation. Be it verbal or physical.
I especially get aroused from things I would consider to be very embarassing or gross in real life. I like it that I would be helpless to do anything about it.

One of my fantasies would be being used as a footstool by a domme as she casually talked to another person sitting next to her on the sofa. They would talk about me as if I wasn't there. I would be all gagged and plugged both ways. Also just to be humiliated I would be forced to clean the domme's feet with my tongue as I would be kneeling infront of her. The things I mention in this fantasy, for me, are a few of the most humiliating things I can think of.