Rats are small, shovels are big, and they are big heads. The mouse is in front. The shovel is in the back. So the mouse pulled the shovel-the big head was behind. Metaphorically, things are just the beginning, and bigger or more important or more serious things are yet to come.
Others: the mouse swings on the swing-fighting internally and sleeping with the cat-practicing courage, the mouse fights three times and six times-covered in evil, the mouse plays the piano-talking nonsense (playing), the mouse bites melon seeds-Qiaozui Zhang, the mouse bites the cat-lawless, and the mouse rides the cat-what courage?