Dogs; Hump your leg and stuff on the floor sometimes even with training or stuff outside and make you spend hours cleaning it all up.
Puppies; Hump your slippers and urinate/stuff on the floor.
Cats; Sit on your lap and keep it warm then stuff in the litterbox.
Kittens; Play with your slippers and urinate/stuff in the litter tray, sometimes on the floor since their bowels aren't trained.
You choose.