rndpic | An App Engine application serving random Picasa Web images | Continuous Deployment library

Firstly, you're not calling an event. Events are raised and not by you. The only simple way to raise a Click event on a PictureBox is to click it with the mouse.

What you're talking about is calling a method. An event handler is not an event. An event handler is a method that gets executed automatically when an event is raised. Calling an event handler directly is really poor practice.

What you should be doing is putting the code that you want executed into its own method that has a parameter of type PictureBox. You can then call that method from the Click event handler(s) of your PictureBoxes and from anywhere else you want as well. If you do that then you don't have to even think about any Click events in this case and that's how it should be, because there is no clicking going on.

If you're doing the same thing for each PictureBox then there should only be one event handler for all the PictureBoxes. If you want to execute the code for a random PictureBox when you click the Button then you pick a random PictureBox and pass it to the method. E.g.