This is conjunction with your previous thread about having trouble lunging makes me think that there is a pain issue involved especially if he is not doing these things when you arent asking him to do any work.
I would seriously suggest at this point that you get a chiro or vet out to have a look at him. If pain is the problem then that can be sorted. If he is just being a little snot you need to go back to basics like what was spoken about in the previous lunging thread. IF he is playing up due to lack of respect for you, you need to get that respect or things will get worse and I fear for your safety. It already sounds as though things are worse than when you first posted your issues with him.
If you go to the frank bell site www.horsewhisperer.com
and you can order a free dvd from them that will give you the basics you need to start getting some respect from your horse. Although a full frank bell or parelli, clinton anderson or marv walker package would be best, some people just can't afford those things and a little info to get your started can be invaluable.
All the best and let us know how things go