The term ASMR was only coined in 2010, though the feeling had been felt and described in blogs and online discussion forums as early as 2007.
Jennifer Allen was the first to use the term ASMR.
She coined the term ASMR to describe the tingling euphoric sensation she felt after seeing numerous others sharing similar experiences online.
While not a scientist, Allen realised ASMR was a shared phenomenon and sought a way to understand the feeling better. 
Names online at the time, such as 'brain-gasm', didn't have quite the scientific ring she was looking for.
Eventually, Allen settled on the acronym ASMR for the brain tingles she and others experienced.