Sound ?
Lot of question marks here.. how intelligent are these toe-ticklers.. They live like wolves in packs, so it's rather an animal. Maybe it likes the sound ? just the right frequency ? By the way I don't think this could be a truely wild hunter.. although humans and apes appreciate tickling, I doubt effective tickling could happen without consent ! What's the role of toe-ticklers in human society ? How come these animals are allowed to tickle girls.. The toe-tickler could be the girl's pet.. or is it some kind of cultural habit humans learned, because wild ticklers are really good at tickling toes ? But in that case why only girls and not the rest of us mammals who like tickling and make high pitch sounds like e.g. my grandmother does (I'm lost now)
http://www.bbc.com/earth/story/20170518-why-humans-chimpanzees-and-rats-enjoy-being-tickled