Dim sObject As Shape
For Each sObject In ActiveSheet.Shapes
    If sObject.Visible = False Then
        sObject.Visible = True
    Else
        sObject.Visible = False
    End If
Next

If ActiveSheet.Shapes("Rectangular Callout 6").Visible = False Then
    ActiveSheet.Shapes("Rectangular Callout 6").Visible = True
Else
    ActiveSheet.Shapes("Rectangular Callout 6").Visible = False
End If