2017-12-11:
ASMR

Autonomous sensory meridian response (ASMR) is a pleasurable, euphoric physical sensation characterized by a tingling of the head and scalp. It's also being referred to as "brain orgasms", and it's typically triggered by soft voices, cracking or crinkling, personal attention, listening to repetitive sounds, or watching people perform mundane tasks. There's a rather large community of people producing ASMR videos with the purpose of inducing this response.

As there are few scientific studies on this topic, there's not yet a plausible explanation for this phenomenon.