First scald the tea bag with hot water. Sweeten with half a teaspoon of sugar. Let the tea steep for about 3 minutes, then remove the tea bag. Let the tea get cold.
Pour the cold tea into a sufficiently large glass (approx. 500 ml capacity). Pour milk on top and add the sweetened condensed milk. Since this is very thick, it is best to use 2 spoons - one is used to pick up the condensed milk and the other to wipe it off. Depending on how sweet you would like it to be, you can take more or less of it. Mix everything well and fill up with ice cubes. Wait a few minutes so that the ice cubes can cool the drink well and the slightly different iced tea is ready.