一不做， 二不休

一不做， 二不休 [yī bú zuò èr bù xiū]

1. ■ stick to a thing once begun; A thing once begun will not be put off until done.; be determined to go the whole hog; carry a thing through, whatever the consequences; go a great length; In for a penny, in for a pound.; Once it is started, go through with it.; One may as well be hanged for a sheep as for a lamb.; Over shoes, over boots.; We must go through with a thing, once it (is) started.