Tkinter askquestion dialog box

The problem is your if-statement. You need to get the result from the dialog (which will be 'yes' or 'no') and compare with that. Note the 2nd and 3rd line in the code below.

def deleteme():
    result = tkMessageBox.askquestion("Delete", "Are You Sure?", icon='warning')
    if result == 'yes':
        print "Deleted"
    else:
        print "I'm Not Deleted Yet"

Now for as to why your code seems to work: In Python a large number of types can be used in contexts where boolean values are expected. So for instance you can do:

arr = [10, 10]
if arr:
    print "arr is non-empty"
else:
    print "arr is empty"

The same thing happens for strings, where any non-empty string behaves like True and an empty string behaves like False. Hence if 'yes': always executing.