>>491996I always had associated キュン with a positive meaning, because of 萌え萌えキュン (moe moe kyun). And at the end of the stream when Pekora says "poketto kara kyun desu" my heart definitely whent kyun too.
Anyway like the other anon said it looks like it became a meme because of the song ポケットからキュンです Now I hope she can sing it too one day.