Mathieu introduces his friend Arnaud, who is French and who is talking very loudly. It’s obvious he’s drunk too much. Clairement, il a trop bu ! He shouts: on va manger, bande de schmet ? Which translates as, “Are we going to eat, you bunch of… schmet?” So schmet is a bit of Belgian slang worth knowing, since you might hear it some time, although I don’t recommend saying it unless, as Hugo says, you want to insult someone. It means “jerk” basically, which is why everyone in the bar laughs.