Go out on a limb.

Expression: "Go out on a limb."

Meaning: Think of this like climbing up a tree and going out on one of its limbs to rescue a cat. The limbs are weaker than the trunk, so going out on a limb adds the risk of the limb breaking under your weight. If the limb breaks, depending on your height off the ground and how you fall, you may suffer injuries or even death. Over time, this expression has evolved to mean taking a risk, even when an actual tree is not involved.

Example: "I have been unemployed for a long time. My friend went out on a limb for me and recommended me for a job."