I have to have a back-up of the essentials at work in case I somehow forget something. I've forgotten both socks and underwear in the past. So I have a spare pair of pants, socks and a spare shirt at work.

My shoes and belt stay at work permanently so I don't have to worry about hauling or forgetting those.

I figure if I forget the underpants I can go commando for a day and it won't kill me.