How do I fold side-income into our budget so my husband doesn't know?
Maybe you can just hang onto the cash and upgrade the things you buy for cash now a bit.  Buy the better cut of meat, the nicer pair of shoes, etc. Since you have no trouble with bending the truth a bit.. if challenged, the shoes were "on sale". And no you must have lost the receipt.  Not that I'm advocating it, but the only time I notice my better half's shoe habit is when a garbage bag of the old ones goes out the door.