¿cómo se llaman los chicos? te llamas marco y felipe. se llaman marco y felipe. les llaman marco y felipe. me llamo marco y felipe.

The answer to the question:

¿Cómo se llaman los chicos? (What are the boys called?)

Se llaman Marco y Felipe (They are called Marco and Felipe)

Is a good example of the usage of a Reflexive Pronoun to change the meaning of the verb, accentuate the action or indicate that the action directly affects the subject.  

Here the Reflexive Pronouns according to the subject are:  

1st person singular: Yo (I) me  

2nd person singular: Tú (You) te  

3rd person singular: Él/Ella/eso/esa (He, She, It) se  

1st person plural: Nosotros (we) nos  

2nd person plural: Ustedes (You) (In latinAmerica) se / Vosotros (In Spain) os    

3rd person plural: Ellos/Ellas (They) se  

In this case the subject in the sentence is the 3rd person plural ellos (they) which are Marco and Felipe. Therefore the correct reflexive pronoun used to give emphasis to the verb llamar in present tense and to express the action directly affects the subject  is se.