So this is the same one as Sanemi's but now It's Giyu. You were petting a cat and Nezuko saw that and gives Giyu fake cat ears.

So you were petting a cat and Nezuko saw that. So she went to Sanemi with fake cat ears. And then he sees you petting a cat so he quickly wears the cat ears and comes to you , grabbing your wrist and puts it on his cheek and smiles.