Its actually a word created by a cute 24-year-old guy who doesn't actually look like 24 but 14. He would say the word if someone compliments him. He felt burdensome when people say good things to him.
Lay : Xiumin hyung is so famous.
Xiumin : Tekk tekk tekk!
Lay : He's well known.
Xiumin : Tekk tekk! Stop!