Oh my.... I just realized they really love to flip their hairs to each other.. 0:

Their way of not-too-obvious eye contacts and smiles. And goodbye. Aww, but this moment was still being caught by their fans! XP 

http://jjungcat.tumblr.com/post/80667636219/taengsic-way-of-saying-bye-to-each-other-is-by

P.S. GIF credits to Google Images. And ohmygod, I can't help but have to post these! This couple is TOO ADORABLE XD