If our message set consisted of the words of the english language spelled out using the 26 letters, then anytime a "Q" was received it would be known that the next letter is "U", and so no information is actually communicated by transmitting the "U"
Hey, Percy, ya typin' on a qwerty keyboard or a Dvorak?
List of English words containing Q not followed by U (admittedly essentailly all borrowed from other languages).
Carry on, nothing more to see here.