The phrase "letted out bag" can be replaced with a number of synonyms, depending on the context in which it's used. Some potential replacements might include "let the cat out of the bag," "spill the beans," "share a secret," "reveal the truth," "give away information," or "uncover a secret." All of these phrases communicate a similar idea - that someone has shared information that they were not supposed to, thereby revealing something that was meant to be kept hidden or confidential. To choose the most appropriate synonym for a particular context, it's important to consider the tone and meaning of the surrounding text.