I first learned about ASMR while driving my car listening to a segment of This American Life. It's fascinating.
Autonomous sensory meridian response (ASMR) is a neologism for a perceptual phenomenon characterized as a distinct, pleasurable tingling sensation in the head, scalp, back, or peripheral regions of the body in response to visual, auditory, tactile, olfactory, and/or cognitive stimuli. The nature and classification of the ASMR phenomenon is controversial.For those who want to explore the subject, Act Two of the TAL podcast is mesmerizing (just click the little forward arrow below "A Tribe Called Rest." The entire segment lasts about 15 minutes, but try it for just 3-4 minutes...).
Reposted from 2014 to add the video above, depicting unintentional ASMR in the movies. Via Kottke.