float x1, y1, x2, y2;

void setup() {
  size(500, 500);
  x1 = width/2;
  y1 = height/2;
}

void draw() {
  x2 = x1 + random(-5, 5);
  y2 = y1 + random(-5, 5);
   
  line(x1, y1, x2, y2);
   
  x1 = x2;
  y1 = y2;
}