Grooming, yes! Rats groom each other to establish social order, their place in the hierarchy, to communicate approval or disapproval. Rats will groom you - hope they do and encourage them. I'm realizing almost every way I touch my rats is some form of grooming them. Petting is not just snuggling. When I scritch my rat - where scritching is a combination of scratching, itching, rubbing, massaging, tickling, stroking, nuzzling, cuddling - I may signal approval, or disapproval, of her behavior. There are lots of forms of grooming and I hope to show many of them, because I'm trying to learn to scritch my rat with awareness and signal something deliberate in my intention. I want to communicate in her language.