上课铃声比忐忑还忐忑下课铃声比悦耳还悦耳
[shàng kè líng shēng bĭ tăn tè hái tăn tè xià kè líng shēng bĭ yuè ĕr hái yuè ĕr]
'Class Bell Sounds More Unsettling Than Anxiety and After-school Ring More Beautiful than Sweetness.' It's humorous and exaggerated, describing how the school bell at the start of class feels tense and uncomfortable, while the end-of-class bell feels pleasant and liberating.