It is often used to suggest that people reveal their true selves when they are under the influence of alcohol, as inhibitions are lowered and they are less likely to be guarded with their words and actions.
However, it's important to note that the phrase is often used in a humorous or lighthearted way, and it's not necessarily meant to be taken literally. It's also important to be mindful that excessive alcohol consumption can have negative consequences, and that intoxication should not be seen as a reason to excuse or condone inappropriate behavior.