A Three - Call someone a three when they think they're hot stuff but a

Call someone a three when they think they're hot stuff but are just average at best. They're like a lukewarm cup of coffee on a cold morning.

You: 'Why does he think he's so cool?' Me: 'He's a three.'

DM: 'He asked me out, and I said no. He's a three.'

Text: 'He said he's going to be a star. He's a three.'