半夜在校长家楼下唱忐忑
[bàn yè zài xiào zhăng jiā lóu xià chàng tăn tè]
This translates to singing 'Anxious' (a Chinese song) outside the school principal's home late at night. It conveys mischief or perhaps an attempt to relieve stress or express feelings through music in an unconventional setting.