Why do his friends cheer when I text him?

Super weird question. But a guy I’m talking to, I’m pretty sure he’s told his friends about me because they all know who I am and he’s invited me to go to their party. But the other day, I texted him inviting him out with me, and I don’t think they saw me but he showed his phone to his friends and they all cheered very loudly when I messaged him 😂 is this normal boy behaviour?
Why do his friends cheer when I text him?
Post Opinion