I came up with this idea mostly as a bit of fun between friends but then I watched a movie called A silent voice and I realized that this idea could be useful for the deaf / mute.
Basically there is a new keyboard called tap this is the website www.tapwithus.com in case anybody is interested
Anyway the basic premise of the keyboard is finger combinations = letters. this can be easily done say if you are holding somebodies hand or something you can make out what fingers they are applying pressure with a little practice. for example each of the 5 fingers is a vowel (aeiou)
Here is a demonstration: