Catch your death - Idioms by The Free Dictionary
catch your death
catch (one's) death (of cold)
To become ill with the common cold. This phrase is often used hyperbolically. You'll catch your death of cold if you leave the house with wet hair—it's freezing outside! I hate going to the doctor's office—I always seem to catch my death after being around all those germs!
catch your death (of cold) catch a severe cold or chill. informal
catch your ˈdeath (of cold) (old-fashioned, informal) (usually said to emphasize how cold it is) get a very bad cold: Don’t go out without your coat — you’ll catch your death.