alelectromigration:
Yep, wedding rings are prone to slipping off or getting lost. But put a thick enough ring of fat around each other waists and you've claimed each other for good. Plus sausage fingers help hold a ring on tight.
There's also the aspect of fattening each other up "so no one else will love you". It both reduces the tempters and the temptations. Letting yourself go demonstrates trust and commitment.
Can’t disagree with any of that, plus, it’s just fun!