Wiggle your Toes
It wasn't that L hated socks. In fact, all things considered, he didn't have a preference one way or another. Most assumed it was just a silly quirk of his, but really, when did L ever do anything without a purpose?
The fact was, the crisp, stinging cold of the air-conditioned room biting away at his toes was a welcomed feeling, especially amidst a grueling case. After spending days and days in front of his monitors with no lead in sight, it was easy to lose hope and be tempted to slip the file with the other cold cases. But then, he would wiggle his numb, freezing, near-frostbitten toes and tell himself that this pain was nothing compared to the pain the victims felt. And suddenly he would be motivated once more to never give up.