It’s always a good idea to have some emergency cash with you for those unforeseen circumstances. And ideally you’ll have it in a spot that’s not your wallet in case you lose your wallet. Which leaves only a few spots to stash that cash including the sock. Sock money is gross people, just don’t do it. Instead get yourself a keychain Cash Stash which is just a tiny tube on a keychain that allows you to store a rolled up dollar bill. It can also be used to store pills.
World Notgeld, 1914-1947: A Guide & Checklist and Other Local Issue Emergency Money (English and German Edition)