간당간당하다 means "be on the verge of" 그의 목숨이 간당간당한다. He is on the verge of death. 차에 기름이 간당간당한다. We've almost run out of gas.

does it go like this: 목이 간당간당 하다? If it is, then it means "your life is on the brink". Basically, you can imagine someone/something being on the verge. Fit to describe a tightrope walker