The world of Pair of Normals is kind of like our own, but not really. #Horsecore is completely made up for this series, but it ~could~ totally be real. ASMR on the other hand, totally is real.
ASMR (Autonomous Sensory Meridian Response) refers to a secretly popular genre of Youtube videos designed to give the viewer a sense of calm, serenity, and/or a pleasantly tingly feeling starting at the back of the head. ASMR "triggers" include soft speaking, whispering, sound effects like tapping, turning pages or rain, and visual stimuli like hand movements or a flickering candle.
#Horsecore is a genre of EDM made up by C-Biz, which includes digital horse noises. In the world of Pair of Normals, it's exceptionally popular, following in the footsteps of (actually real) genres like seapunk, witch house, and vaporwave.