Definition
To completely believe a deception or falsehood; to be easily tricked or fooled.
完全上当
The scammer said he needed money to help a sick child, and she fell for it hook, line, and sinker.
骗子说他需要钱帮助一个生病的孩子，而她完全上当了。
He told me he was a billionaire, and I fell for it hook, line, and sinker, how foolish of me.
他告诉我他是亿万富翁，而我完全相信了，我多么愚蠢啊。
She swore she hadn't stolen my wallet, and I fell for it hook, line, and sinker.
她发誓她没有偷我的钱包，而我完全相信了。