Thanks, I'm just a concerned parent.
I agree with Mark. And, I don't think that a two year old is even going to be able to learn to behave that way. So, I would think that it is normal. Especially since he is doing it when he is really tired. Got a feeling that it is more his way of unwinding.
And yes, it is uncomfortable to watch. You could try and distract him. But, I think he is kind of telling you that he is tired. or even if he is not - put him in his bed and let him go.
Recently he's been making the gestures when he's really tired and trying to go to sleep. I've done a lot of research and I've read that, they are just discovering themselves. I've read also that other parents just go ahead and let their children make the gesture of humping their sippy cup, toys, and stuffed animals. But they tell them to do it when they are by themselves. But my son making the gesture of trying to hump feet and his cup, make me feel uncomfortable with this situation.
When you use the word 'hump', this implies sexualized behavior. I am almost positive that a 2-year old isn't going to demonstrate sexual behavior unless he learned to behave this way either by something he viewed or a sexual act done to him. I would suggest that you discuss these behaviors with your son's pediatrician as it sounds like he may have a developmental issue or perhaps a victim of sexual abuse. It is difficult to determine why he behaves this way without a thorough evaluation.
Does he act in any other odd ways or is this the only one? If so, you should consult with a developmental pediatrician as to why. He may be stimming; which is a way people with developmental problems comfort themselves. If not, there needs to be a direct consequence to this behavior. For example "IF you hump anyone or anything, THEN you get no computer time or no sweets, etc." My daughter used to love to spit on people and that's how we got her to stop.