Both DS's (18 months and 3.6) hate having their hair washed. I hardly ever do it for this reason but they're having their photo taken tomorrow and it was looking a bit yucky. DS2 I managed without too much upset by wrapping him in a towel and holding him across my knee, over the bath and then washing hair being very careful not to let any water / soap on his face.
DS1 bigger and a lot stronger. We tried sweet talking him in to it (worked a few months ago and he was completely happy having it washed for a while) but then we decided force was necessary. Tried same tactic as with DS2 but ended up with bathroom floor flooded, shower screen half kicked to bits, DS2 frightened and sobbing his heart out and DH and I shaken and feeling like very bad parents indeed.
It was a disaster and not how it should have been handled but I'm at a loss. I don't have the energy and patience to negotiate endlessly with a 3 year old just so we can get basic tasks done (it's not just hair washing...)