Make any string sarcastic!

sarcastify.py

def sarcastify(my_string):
    """
    Returns a sarcastic version of the provided string.
    
    Example:
    >>> sarcastify('Do you really think that\'s a good idea?')
    "dO YoU ReAlLy tHiNk tHaT'S A GoOd iDeA?"
    
    Useful for arguing online or replying all to that email that accidentally
    went to the whole company.
    """
    a = my_string[0::2].lower()
    b = (my_string[1::2]+' ').upper()
    mY_StRiNg = ''.join([i+j for i,j in zip(a,b)]).strip()
    return mY_StRiNg