Mixing vodka and Red Bull is a popular concoction for those trying to stay alert while drinking.

However, a new study published in the Journal of Psychiatric Research suggests this potent mix compounds the effects of heavy drinking, and increases the “risk of fighting, violence, and participation in risky behaviors.”’

In other words, Red Bull vodkas turn people into belligerent bros.

Speaking to Science Daily, the study’s co-author Dr. Matt Parker of the University of Portsmouth, said, “This study is the first to show that the two together may be exacerbating some of the negative effects of binge drinking.”

Working with researchers from the Federal University of Santa Maria in Brazil, Parker tested how alcohol and taurine —the key energy-giving ingredient in drinks like Red Bull— altered the behavior of 192 zebrafish. Yes, fish. The pun didn’t escape us, either.

The fish were divided into different shoals, and exposed to either just water, taurine and alcohol separately, or taurine and alcohol together. The behavior of each group was analyzed at different time intervals for a period of one hour.

Scientists concluded that the fish exposed to both alcohol and taurine displayed more “risky” behavior (spending longer time in areas where they might be at risk from predators), and had fewer social interactions with other fish.

“Alcohol reduces our inhibitions, and in low doses can cause relaxation and euphoria,” Parker said. “However, in higher doses, this low inhibition can cause problems with fighting or risky behavior.”

So the next time you’re in the middle of an unavoidably long drinking session—a wedding, for example— it might be wise to think twice before ordering that one-two punch.