Deezer's Lemonade is made of goodness! Four special ingredients from sunny, non-irradiated environments poured in one cold glass!”
A refreshing can of lemonade produced by Deezer in Covenant. The can itself appears to be a purified water can with the labels scribbled out, and a hand written cardboard label taped to the front of the can.
Deezer's lemonade is not made from real lemons and the ingredients are often being questioned by the passersby.
There are several clues as to the content of the lemonade and its "Four special ingredients" - Deezer sometimes says "Less mutfruit, less rads, same great taste!" indicating that there is some mutfruit in the beverage, and its presence in a modified purified water can paired with the ability of Mr. Handy robots to produce purified water (as shown by Codsworth) make water the most likely additional ingredient.
The other two ingredients are unknown, but Strong does indicate that the liquid is yellow and there are many NPC conversations about it tasting odd, so it is unlikely that it tastes in any way like traditional lemonade.