A proverb meaning that once you've committed to something (often something bad or risky), you might as well go all the way — 'in for a penny, in for a pound.'
借金してギャンブルを始めた彼は、毒を食らわば皿まででどんどん深みに嵌った。
He started gambling with borrowed money and, once committed, sank deeper and deeper.
仕事を引き受けたからには毒を食らわば皿まで、最後までやり遂げるつもりだ。
Since I took on the job, I'm going to see it through to the end — in for a penny, in for a pound.