The 'No. 1 Song on My Birthday' meme is a popular social media trend where users look up the top-charting Billboard song from the day they were born and pair it with a reaction image or video. This trend taps into collective nostalgia and the humor of 'musical destiny,' where a person's vibe is jokingly judged based on their birth hit. It often leads to hilarious results, as users either celebrate being born to a masterpiece or express mock horror at being associated with an obscure or embarrassing one-hit wonder. The meme is highly shareable because it is personalized, encouraging friends and followers to look up their own songs and join the conversation.