Well yes I have, but only once before. A couple of post ago.
The history of the G&T as stated in Wikipedeia:
Tonic water contains quinine, which was used to prevent malaria. In the 18th century, tonic water contained a large amount of quinine, which caused it to have a very bitter taste. Gin was added to make it more palatable. Tonic water sold today contains only a very small amount of quinine and is consequently much less bitter (and it is sometimes sweetened).
Because of its connection with warm climates and its refreshing effects, gin and tonic is a very popular cocktail during the warmer months"
So, it was invented as a cure for malaria. Its nice to know that these one thing I'll never die of.
Speaking of cures: