Rice balls are a traditional Japanese food. They consist of balls of white rice stuffed with various salted foods and wrapped in seaweed. They usually look something like this:
Babies are a type of human. They're like regular humans, but smaller. They often have some extra fat on their bones, known as "baby fat." They usually look something like this:
Japanese comedian Masahiro Ehara noticed that when he squished his babies' faces, they kind of looked like rice balls.