The more the merrier

[Zipporah Schumaker]

It means what it says, the more people the better everything will be.
It is also used [sarcastically] when [an unwanted] person is invited or [invites] himself.

[Sarah]

Is a phrase employed by men who enjoy the company of other men. It means, literally, the more people who are around the happier the occasion will be. However, scholars [extrapolate] that people is a [stand-in] for the word men. Therein the phrase is really means that an occasion is made more entertaining by the increased number of men in [attendance]. Clearly, the speaker of such a phrase is excited by the additional men who are around or near him.

[Merna]

used to say an occasion will be more enjoyable if a lot of people are there: