Start writing things down and then contact a local equal opportunity office and start the process. It will not be cheap for them. If people keep doing this they'll change their ways.
Going public on Twitter or Hacker News though hasn't done much other than bring out nasty and unproductive fights between Social Justice Warriors and Men's Rights fanatics. They make everyone look bad and we all walk away feeling like maybe we've lost faith in humanity when in reality a serious problem just stems from mostly unintentional, but hurtful ignorance.