Sloths just hang upside down all their lives, they eat, sleep, mate, etc, upside down. They also only defecate when it rains so their predator the jaguar or other animals track them from their duty.
The common name of "sloth" is derived from the Old English word meaning "lazy" and "sluggish". Although this term may be misleading when applied to a sloth, one cannot deny that they live very quiet...