The more the merrier interjection spoken language slang
Cụm từ này là cách nói thông tục, thân mật.
"Can I bring my girlfriend to your party?" "Of course yes - the more the merrier!"
Children enjoy playing game together, the more the merrier.
Oh sure, you can come to join us for lunch —the more the merrier!
"Do you mind if my friend comes along?" "Not at all! The more the merrier!"
An unexpected last-minute invitation
To invite someone to have dinner at a restaurant and pay for the meal.
To give an invitation for one to join in an activity with someone else (or a group).
This is a 'fixed' comparative usage.
This idiom is first found in John Heywood's 1546 Glossary "A Dialogue Conteinyng the Nomber in Effect of All the Prouerbes in the Englishe Tongue":
"Haue among you blynde harpers (sayd I.)
The mo the merier."