You saw him fighting with his girlfriend and he looked miserable so you decided to help him.

"Liam! Who is she?! Don't you know I'm pregnant? How could you cheat on me?" You fake cried. He was startled and confused when he saw you but went with it as he realized

His girlfriend looked at you and was furious as Liam hugged you and played along, asking for forgiveness. They then broke up finally and she stormed off.

"Pay up." You ended your acting.