Place the iced tea in a liquid measuring cup. Add in the rum.
Squeeze in the lemon juice and stir.
To serve, pour into two cocktail glasses (with ice, if needed) and garnish with lemon slices.
Notes
You can buy a jug of sweet iced tea for convenience. Or, make it using a powdered mix. You also could steep black tea and then add sugar to taste.For an 8-Quart Pitcher of Iced Tea & Rum Cocktails:You'll need 6 cups of sweet iced tea, 1 ½ cups of rum, and ¼ cup of lemon juice. Pour it over ice in each glass. Store any leftovers covered in the refrigerator.