Chi ties up Dragonfly in his own cables as a punishment for abducting and trying to rape her.
Chi: Only the one just for me can ever come inside.
The awesome increases when she hits him so hard with that concussive blast attack that he passes out. To top it all off, she causes what is easily thousands of dollars in damage to his house.
The anime ending when Chii uses her powers to give all the Persocoms a true sense of self and individuality.
The final boss encounter from the episode Chii Plays. After having spent three all-night sessions of Level Grinding and questing to find Chii, who is always mysteriously absent whenever they log on to the game, Hideki, Shinbo and Sumomo are faced with the final boss of the game, a boss nobody has been able to beat as of yet. While Shinbo and Sumomo beg him to go back, Hideki jumps into the fray without a second thought; sure that Chii is only a small distance away. The battle goes as well as you'd expect for the party and and they're all defeated with one hit a piece. At the end of his rope, Hideki calls out for Chii who then shows up as Hideki's summoning magic, and one-hit-kills the boss using the same blindly bright force that Freya uses to defend her. All of this set to the Dark Chii theme. Yes, it was all just a game but IT WAS AWESOME!