You throw it out. Better safe than sorry.
Red meat that turns blue when exposed to air is typically safe to eat. The blue color is caused by a reaction between the meat's myoglobin and oxygen, rather than being a sign of spoilage. However, it is always important to trust your senses and check for any other signs of spoilage before consuming.
Tongues are usually not blue unless you are totally lacking in oxygen -- or you have been eating blue food!
it turns blue
Pink Turns Blue was created in 1985.
If a duck egg turns black and blue, it means that the fetus is not getting enough oxygen. It will most likely die.
It means that it has been exposed to excessive heat.
Blue litmus turns red in the presence of an acid and remains blue in the presence of a base.
It turns delicious!!!
Blue Turns to Grey was created on 1965-12-04.
Red/blue red turns to blue to detect alkali blue turns to red to detect acid
You probably mean litmus paper. (see https://en.wikipedia.org/wiki/Litmus.)
this may show it works.