“信口开河”，汉语成语，字面意思“speak carelessly, rapidly, voluminously like the outflow of river water when the sluice gates are opened”。比喻随口乱说一气，指说话没有根据，不可靠（speak without measuring one's words）。可以翻译为“talk through one's hat”，表示“talk nonsense”。
- 别理乔纳森。他又在信口开河了。
Don't pay Jonathan any mind. He's just talking through his hat again. - 别信口开河！昨天他不可能见到我，因为当时我不在那里。
Don't talk through your hat! He could not have seen me yesterday, because I wasn't there.
