I am coming - when you are going
15/02/2013 13:34
Saying "I am coming" when actually you are going is grammatically incorrect. This often happens when you are leaving a place with the plan of coming back. It is such a confusing statement.
Rather say
I will be back (soon)
Give me a sec (when you need the person to excuse you for some mins).
You can add some other alternatives in the comments.