Of period and a confused Jiyong. 

Yoona's a girl. Jiyong totally understands that. But what he doesn't understand is when she gets her time of the month. First of all, Jiyong is Yoona's bestest friend in the whole wide world (according to Jiyong) so he knows her inside out, like the palm of his hand...except those days in a month.

No, those days it's like taking on a whole new level. Yoona's more sarcastic, gets angry a lot, paranoid at the simplest things, gets emotional a lot when Ji teases her (usually she'd just back and he'll admit defeat but that's on the off days), shouts about people not understanding her, gets moody, cries watching a sappy movie, and a lot more craziness that Ji has to handle. He completely does not understand how PMS can make a lady turn into such a lion. A cranky lion.

He knows that it comes once a month and last for about 1 week (hey his done his personal research about it and it's not something he would like people to know). Jiyong sees everywhere in the commercials about this new brand of pad that keeps the girl in the video happy and active. So one day he decides to buy it, with the help of Yuri of course (God knows what he'll do if people found out his buying those kind of stuff) and gave it to Yoona on one of her period days and he welcomed the almighty fist of Im Yoona on his forehead.

Jiyong doesn't understand her when she's on her periods, no he does not, not even 1%. She'a just unpredictable, very. And instead of having a best friend, he feels like he's having a grumpy old wife in exchange. Ji still stays by Yoona's side cause he knows underneath all that crocodile skin is his Yoong. Lovely and beyond beautiful. So for now he thinks he'll just hang on to Yoona and follow her period ride.

Hey,atleast it's not forever. Ji read on the internet once (okay maybe twice) that pregnant women stop having their pms. And that lead Jiyong to have wild thoughts for the rest of the day. Or maybe for the rest of his life until the day he can actually stop Yoona's pms...(insert smirking smiley here >> ;))