Tā yǐjīng shīyè le, nǐ hái pīpíng tā, zhēnshì luòjǐng-xiàshí.
He's already lost his job, and you're still criticizing him - that's really kicking him when he's down.
Tips
memory
Literally: 落 (fall) + 井 (well) + 下 (down) + 石 (stone). Imagine someone tumbling into a well, and bystanders throw stones in on top of them. A vivid image for piling on someone already suffering.
