If you find yourself asked to do something you don't want to do on the wards/theatre/clinic, here is somethings you can do..
1. Stand up to your consultant/ registrar and tell them you don't think it's right and you feel uncomfortable about it ( I personally would not have the guts to do this)
2. Pretend to be ill/ not yourself/ not up to the task
3. Wonder out loud how ethical the situation is
4. Pretend to be confused/ignorant of the laws/ethics applying to the situation ( this is particularly good, because you aren't laying blame on your senior but on yourself but you'd make them think about it too)
5. Kindly decline ( though I doubt this would go down well in the later years)
6. Get on with it and seek counselling after