is it bad to close the mouth of the penis and didint allow to shoot the cum after masturbating
I wouldn't recommend that. It might add pressure, and the semen would flow out once you re-open the mouth anyways. If you're avoiding a mess I suggest getting tissues etc. to masturbate into, and then dispose of them.
You're going to have to let go of it sometime, then it will come out. So why bother? Or are you going to walk around all day holding the tip of your penis?
Just put a sock on it.
Just put a sock on it.