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

https://twitter.com/pesa_africa/status/1031598250967662593 [Nitter]

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

https://twitter.com/pesa_africa/status/1031598551883763713 [Nitter]