ref: Irreversible Explained
It looks like Mourad and Layde are angry because they didn't expect a murder... They were looking to make a quick buck from two well-off guys in agony. After questioning Concha, Mourad and Layde get separated from Marcus and Pierre. The next thing they know someone is dead. Now they aren't getting any money for running around town all night.
Marcus is taken away on a stretcher. Pierre is arrested for murder.
Mourad and Layde are pissed off that they aren't getting paid. And if
the police question Pierre, they know that they'll get pulled into
this. They shout and curse at Marcus and Pierre.
Also, now the two of their names will get pulled in to a murder case. Hence they are swearing away at Marcus and Pierre. The homophobic insults they are throwing is because the incident happens at Rectum which is a gay bar. This shows that Mourad and Layde are in general condescending towards gays. These are the lines that they are shouting (translated):
They still owe me money. What happened? I told you those b####ds
wouldn't pay. Because of those two guys the f##kers got us. Why are we
still standing here? We`ll get our money or go. F##king fags. There
are gays all over here. It's god damn impossible, they are everywhere.
Get rid of that asshole.
