The Three Little Kittens are characters from the nursery rhyme, "Three Little Kittens," known for losing their mittens.
They appear in a 2012 episode of Sesame Street, where Telly recruits them to help find Gordon's glasses so he can read the new Furry Potter book to him. The kittens offer advice, singing a song, about the time they lost their mittens.
They suggest he start crying and that'll help. Gordon points out that they should look for their mittens, an idea they never thought of. They start looking in Gordon's briefcase, where their mittens turn up (much to Gordon's puzzlement). Now that they've found them, they hope their mother will be proud enough of them to bake them a pie or, even better, read them the new Furry Potter book.