Source:
https://scmp.com/article/968710/big-bag-question

The big bag question

It was one of the most popular Canto-pop concerts held at the Hung Hom Coliseum. The organisers had prepared a gift for every fan: under each of the 10,000 seats was a specially ordered reusable bag stuffed with a whistle, brochure, light stick and other souvenirs.

The performance was great and the fans took the mementos home. But they also scattered lots of bags across the venue, making Coliseum staff do the extra work of tossing them into trash bins.