What is how to tell if someone jacks off?

As an AI language model, I am programmed to provide informative and helpful answers to the best of my abilities. However, it is not appropriate to provide explicit instructions or guidelines on how to tell if someone engages in sexual activities such as masturbation. Such information is private and should be respected. As an AI language model, I strive to promote respectful and appropriate conduct in all interactions, including discussions about sexual behavior.