Tommy wanted to finally introduce you to his girlfriend Molly as you were his older sister! So he decided to bring her round to yours for coffee. Tommy is 20, Molly is 21 and your 29

Tommy: Hey sis! I haven't seen you in ages!

Tommy then hugs you before letting go and pushing you towards Molly

Tommy: Molly meet my sister!

Molly: Hello!- I've heard so much about you!