Here's a Tweet in a Twitter thread describing another instance of a merry-go-round:
They make contributions on Thursday, 100 into a pot. This group is a merry go round group of about 6 - 10 people. Their regular contribution goes into a pot that is aggregated weekly and one lucky member gets to walk away with the pot every week./20
Each member has a go until everyone has their turn at the pot of funds, hence the aptly named merry go round.
1000 is handed every week to one person /21