How do I exit from a function?

i know that in vb.net you can just do Exit Sub

but i would like to know how do i exit a click event in a button?

here's my code:

private void button1_Click(object sender, EventArgs e)
{
    if (textBox1.Text == "" || textBox2.Text == "" || textBox3.Text == "")
    {
        //exit this event
    }
}