If you need to fill a narrow-necked container, but don't keep a funnel stocked around the kitchen, it's easy to make your own out of aluminium foil.
This is about as simple as kitchen hacks come. Just roll up some foil in a funnel shape and stick the small end through the neck of your desired container. I'd recommend rolling it several layers thick to it won't get knocked out of place by a stream of liquid, but it should be fine as long as you pour slowly. A few pieces of tape can also help keep the shape intact.
Real Simple suggests using this to transfer salad dressing and condiments from plastic containers to glass carafes, which would go a long way towards classing up your refrigerator. Check out the source link for more clever uses for foil.
Aluminum Foil as a Funnel [Real Simple]