Funny expression : j'ai un rhume carabiné !

When you have a bad cold

• In English you'd say : I have a bad cold
• In French, j'ai un gros rhume

You may also also say : j'ai un rhume carabiné. If you translate literally 

• j'ai un rhume : I have a cold
• carabiné : rifled (une carabine : a rifle)

So  "I have a riffled cold"

               Welcome to France, enjoy the French language!