he who rides a tiger is afraid to dismount—unable to extricate oneself from a difficult situation
騎虎難下
ride a tiger and find it hard to dismount—have no way to back down
騎虎難下勢成騎虎（shì chénɡ qí hǔ）qí hǔ nán xià
騎著老虎難以下來。比喻遇到困難，但是為形勢所迫，想不干又會造成重大損失，故不得不硬著頭皮干下去。have no way to back down, be in for it, have a wolf by the ears, up a gumtree, up the people, up the creek, in chancery