"Let it slip" is an idiomatic expression that implies revealing or divulging information unintentionally or carelessly. Synonyms for this phrase can include "reveal accidentally", "unintentionally disclose" or "unwittingly let out". These terms highlight the inadvertent nature of revealing information without intent or awareness. Another possible synonym is "unconsciously divulge", emphasizing the lack of deliberate intention behind sharing the information. Additionally, "drop a hint", "unintentionally let slip" or "inadvertently mention" can be used interchangeably to convey the idea of accidentally revealing information or letting it slip out in conversation or action without meaning to do so.