"During college, how did you spend your summer vacations?"
The best answer is to have spent your summer productively such as working as an intern. Even if you did only one intern, the interviewer will like that. The worst answer is to say you didn't do anything. Or say you worked in the supermarket to get some money so you can party at night. So think of something productive, and if you don't have an intern experience, you can say that you spent your summer learning something new.
"My last two summers of college, I did an intern for a consulting firm. I gained experience working on office solutions for large companies."
"I have a strong interest in traveling, so I used my summer to travel. I went to Europe, Australia, Brazil, and China."
"Every summer, I took extra English classes. I also took some drawing classes because it's one of my hobbies. So I spent my summers learning more things."
"My first two summers, I had to work to save money for tuition. But after saving enough money, I had a free summer. I actually ended up taking some computer classes to prepare myself for the business world. These days it's a requirement to know computers, so I prepared for that."
Although I said don't mention useless work, it is ok if it is for tuition. It shows financial responsibility. Finally, taking some computer classes for the summer is a great way to prepare for work life and it was a summer well spent. Make sure you have an answer that shows productivity.