Ragdoll standing up (both literally for the first time and metaphorically) to Deadshot when he implied that Ragdoll's attempt at consoling a despondent Black Alice was really an attempt to have sex with her. His teammates' reactions matched those of the readers.
King Shark attacking an ARMY of gangsters employed by the Penguin in issue 35. While singing the King Shark song. Which is basically him singing the words "I'm a shark!" at them as he eats them.
The Mad Hatter single-handedly taking down the Doom Patrol in Six Degrees of Devastation.
During the Hell story arc, Liana, Scandal's girlfriend, has been kidnapped by a nutjob former client called Randall who plans to "deprogram" her. One of his methods includes pouring hot sauce into her eyes, which he also did to himself in the first part. The thing is, Liana will not break. Oh sure she cries, but she won't admit she's a horrible person, or a sinner, just to please this psychopath. She even tells him off in the middle of it, saying he's not fit to breath the air of the sex workers he so vehemently believes are evil. And when the Six finally save her, and give her the choice of ending Randall's miserable life, Liana says "no". Because even if Randall doesn't have a relationship with God, she does. Of course, that doesn't stop Scandal from killing him as soon as Liana's out of sight.
When the Secret Six was first put together in Villains United they were nothing more than a group of C and D-List villains no one took seriously or cared about. By the last issue of the series, practically every A and B-List superhero has been called in to stop them. DAMN.
Jeannette's one-on-one fight with Wonder Woman in Depths, until she unleashes her Brown Note power, causing the Amazon Princess to experience Jeannette's botched execution and leaving her a foaming-at-the-mouth heap on the ground. Again, Wonder Woman.
Deadshot telling Amanda Waller where she can stick it by shooting her in the chest.
Issue 23. The team is kidnapped and put on an island so a "Presidents' Club" can hunt them down. The team then shows the Presidents' Club exactly how much they've underestimated them.
Jeannette "persuading" Cheshire to give her the antivenin to the poison she put in the Six's meals... by dangling her off the roof of her casino, flinging her into a mirror, and then threatening to start the torture by putting broken glass in her eyes.