What's the most "old school" way you've ever tracked your spending?

I built Cashflow because I watched my wife sit down every night and write our expenses into a notebook by hand. It made me realize how many people still do this not because they don't know about budgeting apps, but because the apps demand more effort than they save.

Curious: what's your "notebook" the manual workaround you use (or used to use) before finding (or instead of) a budgeting app? Sticky notes? A spreadsheet you update once a month and feel guilty about? Mental math at the register? Would love to hear the real, unglamorous habits people actually have around money.