Milksteak is a meal enjoyed by Charlie Kelly. It was mentioned in the Season 5 episode "The Waitress is Getting Married" where Charlie wants to put it down as his favorite food in an online dating profile. It is later mentioned in the same episode as Charlie orders it in the restaurant.
Mac assumes that the "milksteak" Charlie refers to is a literal steak boiled in milk. In actuality, "Milksteak" is just an egg. In Charlie's mind, the "eye" of the steak isn't actually the bone, it is the egg yolk. Charlie details that he would like the milksteak "boiled over hard" and garnished with "raw" jelly beans which further verifies this. Charlie's usage of the word "milk" is derived from the fact that both milk and egg whites (when cooked) are the same color.