Bharatiya Janata Party on Wednesday demanded a probe into an alleged security breach in Finance Minister Pranab Mukherjee's office. Talking to mediapersons in New Delhi, Senior BJP Leader Sushma Swaraj said the 'chewing gum theory' given by the IB is a big joke and the country wants to know the truth. Calling it a big mistake in the security protocol, Swaraj demanded thorough investigation into the matter.