12 of the Cutest Sloths You've Ever Seen!Don't call 'em lazy: These creatures at Costa Rica's Aviarios Sloth Sanctuary are working it!

BUTTERCUP, THE SLOTH THAT STARTED IT ALL

Kids brought the Arroyos an orphaned sloth in 1991, kicking off their sloth-rescuing operation. Now Buttercup greets visitors and "knows that she is the spokesperson for the sloths of tropical America and takes her duties very, very seriously," says Avey-Arroyo.