A light-hearted and friendly response to someone who asks how many days of summer vacation you have left could be:
"Oh, just a few precious days left! Trying to make the most of every moment before it's back to the daily grind."
This response acknowledges the remaining vacation days positively and indicates that you're enjoying your time off while also acknowledging the reality that it will end soon. It's a casual and relatable way to address the question without going into too much detail.