Save someone’s bacon/neck/skin

To save someone’s bacon is to rescue someone from harm. It dates from the mid-1600s when a side of bacon was a precious commodity in a household and would often represent the difference between eating and going hungry, a potentially harmful situation. To save someone’s skin or neck means to save someone’s life and is even older dating from the 1500s. Skin in this sense refers to the body and neck is an allusion to hanging or beheading.