End of a traditional French dinner. It’s not even Christmas or Easter. It’s not even a Sunday lunch. A normal dinner with French friends. You’ve eaten so much your brain is off. All the words are gone. How will you say “I loved it!” or “Could I have some more?”… Let me help you with a few traditional endings. 
It was very good.
Always a good idea to say it to the cook. All these phrases are ok for a hotel, your in-laws and close friends.
C’était très bon.
C’était excellent.
C’était délicieux.
Could I have some more?
This behaviour is familiar. Formally, people are supposed to ask you : « Je vous ressers ? ». You answer : « Volontiers ».
But with family and friends, it is always ok (Personally, I love it) to ask for more: it shows that you really appreciated the meal.
Je peux me resservir ?
Je peux en reprendre ?
Je peux avoir du rab ?
I’m full
All these phrases are familiar. The behaviour is familiar as well.
Je suis blindée.
Je suis repue.
It means literally “I’m full”.
J’ai la peau du ventre bien tendue.
From the popular song: J’ai bien mangé, j’ai bien bu, j’ai la peau du ventre bien tendue. It means the skin of your belly is tight.
Je ne peux plus rien avaler.
I can’t eat anything else.
J’ai les dents du fond qui baignent.
Careful: this is (light) vulgar. It means: I’ve eaten so much, food doesn’t get down my throat anymore. You’ll hear it as it quite a funny expression.