食べ残しを「持ち帰り袋に入れてください」って英語でなんて言うの？

In some countries, for example South Africa if you ask for a doggy bag it means that you would like your left overs packed since you want to take them with you.

Doggy bag = usually, a plastic bag in which the remains of the meal may be placed so the customer can take them home.
Container = any bag, box, tupperware, basket etc in which something may be stored.

Its an Idiom;-}
"A doggie bag" is asked for by millions of people who have NO DOG!
Its simply a fun way to ask for the " Leftovers" to be wrapped up to take away
with you...We all hate to see good food go to waste
(and we may be hungry later;-))

Doggy bag' is the most commonly used expression in Ireland when asking to take the leftover food home with you. Although it is a ''doggy'' bag it does not imply that you will give the food to your dog. But of course you can if you want. :) Lucky dog! :)

We don't always finish our meal when we eat out.
If we would like the waiter/waitress to pack our food up so we can finish it off at home we can ask by using the sentences above.

Takeaway: a meal we take away from the store to eat elsewhere.

"Ï have lost my appetite, please make this a takeaway?"
"Ï have to rush off for a meeting, please make this a takeaway?"