my pastel like to hiss once and a while and of course hes in his striking position, all i do i lightly touch the top of his head he pulls away and goes into his little head shy coil and then pick him up, touching there head like that when there trying to be tuff is like a dominance thing showing the snake your in control of the situation and the fact that you just touched there head shows them you could have hurt them but you did not so they realize there not in danger. a well knowlaged breeder and personal friend once told me if you have a bp that your holding and it wont stop being head shy and relax to GENTLY barly even touching its head put its head in your fist like wrap your hand around its head you dont even have to be touching its head put your hard around it for a few seconds and they relax, not sure works it works but it does one of my females is very head shy works every time she chills right out. like i said u dont grab its head u dont even need to touch its head for it to work, personally i think it works because it makes them realize your not going to hurt it. so thats a trick i use for hissing and for head shy bp's none of this is scientific and my theorys could be totally wrong but it works for me and may be worth a shot for you