My girlfriend sent me a joke, I don't know what it means.

This is not simple, which means that Xiao Ming's father's function can't satisfy his mother. Seeing Xiaoming hardening the caterpillar with hardener, he thought of strengthening the function in this way to satisfy his mother, so her mother was happy and said that her father was a BMW, so she bought him a BMW. The key is the hardener! ! ! Xiao Xiaoming's father improved some of his functions with hardener! ! !