Before you roll your eyes and discard the white shirt, check out this quick fix.
Mix 2 tablespoons of vinegar with 1 teaspoon of Surf Excel liquid detergent in a bucket filled with a litre of warm water. Soak your stained shirt in the solution for 30 minutes.
Fill another bucket about halfway with warm water and add soap flakes. Create your own soap flakes by grating half a bar of soap. Pour cold water in the bucket once the soap flakes dissolve.
Move your shirt from first bucket to the second and let it soak in the solution for about 10 to 15 minutes. Then, pour two drops of bleach in the bucket and clean the stains. Rinse it until all the soap is removed.
Get rid of excess water and air dry the shirt.
There you go; it is simple and effective.