Attempting to stop the latest social media craze from invading its Lake Superior shipping harbor, the U.S. Army Corps of Engineers is issuing a warning to people poised to jump into the frigid water around Duluth: Don't do it.

Around the country, teens and young adults have been nominated by friends to jump into cold water, sometimes to raise money for causes. Friends typically videotape them nominating someone else, then jumping into a cold body of water.

Last week, a Corps employee stopped a college-aged student from jumping off a Duluth pier into the shipping canal, warning of the cold-water shock "gasp reflex." Jumpers can drown when the automatic reflex to breathe makes them inhale water, Corps officials said.

Besides, they said, it's often against local laws to jump from piers at Corps projects or swim in the federal navigation channel.