In the book of exodus, God instructed the children of Isreal to kill a lamb, dip a brush in the blood and dab (or paint) the lintel of their houses with it.
Danger was imminent.
Since the entire community of Isrealites ,living in goshen, were performing the activity, they were literally PAINTING THE TOWN RED!
Though that time they werent smiling!
But when you think of it, in the morning who was smiling, and who was left with a terrible "hang over" from failing to splash some red?