The Twitter hashtag was started by businessman Dardhan Parekh, a Juhu resident, to encourage 'Net friends' to exchange gifts.
Six days ago, make-up artist Piyu Palkar from Vile Parle added a social-cause element, urging Parekh to set up five special drop boxes in the Juhu-Bandra area and use his Secret Santa programme to encourage Mumbaiites to drop anonymous gifts in them.
"The children were thrilled," said Dr S Banavalli, head of pediatric oncology at Tata Memorial Hospital.
"They are all under 10 and were very excited to get so many gifts from 'Santa Claus'."