Trending @Accenture; How do you guys utilize your sicks leaves or casual leaves?

For me I haven't really got sick in a long time so there was no actual need for me to use sick leave but I would still use it sometimes by saying I am feeling sick or something but for casual leave I have no clue wth is that. I just use it during PL and it seems to be working fine and no one says anything. Is there any other way to utilize them so I can save earned leaves.