Wash the jars out reaaaallly good .

Put a little slit in the top of the lid and use one for a penny jar .

Use one for left over food . Like left over macaroni and cheese . Just make sure you eat the leftovers soon and don't forget them in the fridge

If you like to marinate stuff . Get some pieces of sliced meat , and fill the jar up with some flavory juices an spices , put the meat in , put the top back on , and let it sit over night in the fridge .

Or do it in the morning and let it sit in the fridge all day , and then cook it up at night .