"I dyed my hair green as a concession to the coming Halloween."
Concession denotes yielding reluctantly to a social custom of which you may not approve or couldn't care less about. Is it a passive act? Yeah, sort of. If one's "heart" isn't in the whole costume thing, but one doesn't have the energy to engage in some sort of protest against the custom, well then one compromises and dons a token Halloween disguise.
Put differently, your dyed hair is a sop you throw to all those conformists who spend hours coming up with an idea for a costume, and then spend more time (not to mention money) on making, buying, or renting the costume. Perhaps your motivation is to avoid being called a party pooper by those enthusiastic costume wearers. After all, you reason, there is no inviolable law you're breaking with this little concession.