Superman/Shazam: The Return of Black Adam showed us that even Captain Marvel, a bigger boyscout and nice guy than Superman, can be pushed too far. Trying to kill him is one thing. Even if you offer him a Sadistic Choice between his life and the life of a hostage, he will sacrifice himself so the other person can live without reservation. Try to kill the hostage ANYWAY, even after he's surrendered and he gets dangerous. What happened to Black Adam after that particular act of treachery was the very definition of a curb stomp battle.
Superman and Black Adam, getting acquainted, and Superman basically sums up the core of his entire character and everything he is and stands for in one short, sweet statement.
At the end of the movie Billy finds himself encountering the bullies again in the alley just like before. The bullies try to push Billy around again, and dare him to talk back. When the main bully tells Billy to say something, even 'one word', Billy just gives him a cocky grin. Cue a far away shot showing lightning striking the alley.
Captain Marvel's thorough beatdown of Black Adam at the end is a sight to behold. Cap definitely showcased why one should Beware the Nice Ones.