When you are busy with other things and a phone call disturbs you, it will be difficult for you to take the phone out of your pocket and pressing on the silent button. If you are an Android user, here is the solution for you. Shake2Mute Android App.
Shake2MuteCall is an application for mobile phones running on Android Operating System. You can mute your ringtones by simply shaking the phone, slap your pocket or shake your bag and stop it crying in the moment.
You can set vibrate in silent mode as one of the option. You can adjust the accelerometer sensitivity, that will trigger the mute option for the incoming call.
Shake2MuteCall App has option to ANSWER call (for donators) and MUTING SMS.