Shoe throwing is catching

What drives journalists to hurl shoes?

Actually I have no answer, but one thing I noticed was it appears to have become an epidemic.

Consider this:

Not long ago a shoe was thrown at Bush and also the Iranian President. Following these two incidence another journalist throws a shoe at Chidambaram.

The Home Minister was referring to the 1984 anti-Sikh riots when the journalist, Jarnail Singh, asked him a question regarding the CBI clean-chit to Congress leader Jagdish Tytler.
When Chidambaram averted the question, Jarnail Singh - a Sikh correspondent from Hindi daily Dainik Jagaran - threw a shoe at him.

Which makes me wonder, whether throwing shoes is a communicable disease. :)

journalist throws shoe at chidambaram