Idioms: eat someone for breakfast, eat someone/something for breakfast

자료: http://idioms.thefreedictionary.com/breakfast

eat someone for breakfast: to speak angrily to someone, or to criticize someone. 

• My boss would eat me for breakfast if I asked for more money.
  

Cambridge International Dictionary of Idioms © Cambridge University Press 1998

eat someone/something for breakfast: to deal with someone or something easily and completely. 

• People say she eats her competitors for breakfast. 
• He is a level-headed guy who eats pressure for breakfast.
  

Cambridge Dictionary of American Idioms © Cambridge University Press 2003