Using your mouth and lips to create popping sounds to recreate morse code. This can be used when communicating with friends and coworkers in a new way so no one will know exactly what it is you are talking to each other about.
A bank teller used MCMP (morse code mouth popping) to alert a coworker she was being robbed to alert the authorities without the suspect in question even knowing!
Where you run up to anyone with something in their hands, twat it out and shout poppen at the same time.
Person1:"GO ON! Poppen Sian!", Person2:"OK". Person2 runs upto Sian like a nob and smashes whaterver she has in her hands on the floor and shouts "Poppen!", then runs away again.