-다고 gives the grounds for the teasing and 놀리다 is teasing or making fun: 허리가 길다고 놀리지 말아요 'don't tease her for having a long back', 웃기다고 얘 틀렸다고 놀리고 'they find it funny and tease us for getting it wrong'. The repeated 어리다고 놀리지 말아요, 'don't tease me for being young', turns up here as a song lyric in a quiz round. The tone is playful, not cruel.