a faux pas
A faux pas is when you’re so clueless, you think you’re being cool, but you’re just being a dumbass. People either roll their eyes or throw you out of the party.
I showed up to a dinner party wearing socks with dragons on them and said, ‘I’m the king of this room.’
I told my teacher that I was ‘going to be a billionaire’ by the time I was 10.
I asked my crush’s little brother if he wanted to ‘be my best friend’ in front of his whole family.