如果某人 “不惜一切地帮助你，即使把最后一点家当都给你也在所不惜”，就可以用短语 “give the shirt off their back” 来描述这个人的行为，意思是 “倾囊相助，尽力帮忙”。

例句

Jack is such a nice guy – he would give his shirt off his back to help you out.
杰克真是个大好人，他会竭尽所能地帮你。

I’d give you the shirt off my back to help you pay for your wedding.
为了资助你支付婚礼的费用，我会倾囊相助。

I’m afraid even giving me your shirt off your back will not help me pay for my new house. But thanks for the offer.
即使你倾囊相助，恐怕都无法帮我支付新房子的钱。但还是要感谢你的好意。