Something feels like an electric shock in your heart. because it is too cute or thrilling.
ex) 널 보면 내 마음이 찌릿찌릿해. (because you are too cute and handsome. I get nervous and tensioned)
And also, when you are sad so you feel pain in your heart (or other body parts), you can say it.
ex) 가슴이 찌릿하게 아팠다. (twinge, numbness)
팔이 저리고 찌릿찌릿하다.