This question is asked to check how competent you are in a particular situation. You have to ensure that you are not sounding lazy or unprofessional.

Sample answer:

I remember this event. Every year, my company used to organize a summer barbeque, and this year, the person who was supposed to organize had left for a new job. I used to VOLUNTEER for this before so I volunteered myself for organizing the barbeque this year.

The annual barbeque was a potluck event with some fun activities planned throughout the day. I conducted a survey amongst the employees to see what KIND of activities they were interested in. I made a list of those activities and created teams dedicated to conducting each of them. I also ensured that activities did not CROSS the budget allocated and took care of sending out regular REMINDERS to track the progress of the team. I sent out posters and went through the office floors with a team of people to make sure people are aware of what exciting things we have planned for them and ensure that they arrive at the venue on time. The day of the event was an amazing one. As we had everything planned, the event went on smoothly and everyone had loads of fun.

I RECEIVED great appreciation from the higher management for my organizational skills and everyone said that they had a great time.