Free milkshake
Go to the part of town where all the cows are found. Go up to the cows, not the bull, and tip it over. After tipping it over and it is lying down, select "Milk" to get a milkshake. If you just milk the cow without tipping it, you will get plain milk. You can sell it for 2 Simoleons at the store, drink it, or give it away as a gift.