Imagine: Liam wants to show you he's a werewolf but can't shift so he asks you to hit him.
***
"Hit me."
"I'm not going to hit you, Liam, I told you I believe you."
"Y/N, you're my girlfriend and my anchor. I know when you're lying, so just hit me."
"No!"
"Yes!"
"No!"
"Yes!"
"Fine!"
Slap!
"Oh god. What did I do?"