Coronation Chicken is chicken mixed with mayo, mango chutney, curry powder, raisins, and other spices. It was created as a 'new' type of sandwich to be had during parties in the Queen's Coronation in the 50s.
A Ploughman's Sandwich usually consists of ham, cheese, pickle, mustard, and salad (though it can have other stuff like egg, apple, etc). It's based on the Ploughman's Lunch, an easy lunch for labourers on farms and such.
A Penguin is a chocolate bar with biscuit (like a Kitkat) and chocolate cream in the middle.
EDIT: You must determine which one of us, me or Guppeth, is telling the truth. Choose wisely.