I'm always on the look out to find new ways to interact with my guinea pigs. Aside from lap time and floor time, I was out of ideas. Then I saw on YouTube another guinea pig guardian doing this to their guinea pig so I had to try it for myself. It's called the guinea pig cheek massage, which they apparently enjoyed very much!
This is the side view:
This the front view:
I love the round bottom lip! So cute. :-)