맞팔했어요???? 나보다 한참동생은 처음 꺅.
-> Did you just followed me back? It is my first time that a way too Young person (sis) did it to me. Lol
(Well, I haven't used twitter so far, so I don't know exactly what "맞팔" means.)
정작
-> It means kind of "actually" or "in fact"
For example: He knows my school but, actually not my name. "그는 내가 어느학교에 다니는 줄 알았지만 정작 내 이름은 알지 못했다."
빼꼼
-> It's an expression of action it self, like when someone stuck his/her head in the room or some other places.
예뻐요?
-> Am I/Is it pretty?
꿈뻑
-> It's also an expression of action it self, when someone is saluting/bowing to others.