Dei thambi is a common Tamil colloquial phrase, with dei used as an informal hey and thambi meaning younger brother, so Tamil speakers recognise it instantly from everyday conversation rather than from one single clip. It has spread online through Tamil meme pages, short-form reels and WhatsApp forwards, where creators reuse the shout as a familiar way to address a friend, tease a younger person or start a joke. Its staying power comes from that everyday familiarity: it needs no translation for its audience and works as a cultural shorthand for playful teasing.