What are three elements of Freud in everyday use?

Three elements of Freud that have seeped into the everyday consciousness are the Freudian slip, the Oedipal complex and the superego. 

In a Freudian slip a person secretly reveals a thought they wanted to keep hidden by making a "mistake" in speech or writing. For example, saying "I am so happy I could kill you" instead of "I am so happy I could kiss you" would constitute a Freudian slip that reveals underlying anger or hostility towards a person.

We often use the term "Oedipal complex" without having the first idea what the play Oedipus Rex is about. However, we know that a male who is overly fixated on his mother has an Oedipal complex. We know too that little boys who insist they will marry their mothers are working through their age-appropriate Oedipal complexes.

Finally, we are prone to note that a person who is very moral or uptight suffers from too much "superego," that element of the personality that keeps our wild desires in check.