'ASMR' stands for 'Autonomous Sensory Meridian Response' — the tingling, pleasant sensation some people get from soft sounds like whispering, tapping, brushing or paper-crinkling. ASMR videos (on YouTube and TikTok) are designed to trigger this response and help with relaxation or sleep. Wildly popular since 2015. If your teen watches ASMR, they are using a recognised relaxation tool. Harmless. Not inherently sexual, though a small adult-content subset exists; mainstream ASMR is wholesome.