For those of you who accidentally turn your hair green or blue or some variation in between, I can tell you that mixing equal parts baking soda and shampoo and leaving on your hair for 5-10 minutes actually helps. You have to use cold water to rinse it out though not all versions of this cure said that, it's what I did. It starts to smell like you just put the dye on after a few minutes, which I thought was a good sign. Even though no colour washed out when rinsing it was significantly faded.
It took 17 years of careless and spontaneous hair dying but I can finally join the ranks of those with bizarre colour boo boos.