Don't believe what your school bully tells you.
Always take it with a grain of assault.
Grain of Assault
Explanation
Explain Bear
Okay, listen up, buttercup. The joke is playing on "grain of salt," which means you don't fully believe something. But instead, we've got "grain of assault," making it sound like you should respond to a bully with violence. Because, you know, you're not exactly Mensa material, are you?