Kendall's "Hold my loofah" and the ensuing speech given to spoiled brat Mercedes that ends with "And he and me and WE would all rather go back to Minnesota than spend one more second pretending to be your boyfriend!"
The boys' scheme to kick the fake gangsta Wayne-Wayne out of the group can count as well.
Points should be given to Gustavo; he completely put his trust into the boys with six words: "Let's get rid of Wayne-Wayne."
Isn't that five words?
Names don't count.
The Pilot Episode - After Gustavo tells James that he has no talent, Kendall stands up & tells Gustavo that he's the one with no talent since his last hit was 10 years ago, before jumping on Gustavo's desk, remarking "Here's a new hit for you" and then singing "The Turd Song" whilst kicking Gustavo's rubbish off the desk at him.
And when security starts to pull him away, Carlos, James & Logan get to pull a Big Damn Heroes moment, with James calmly replacing the microphone he was holding, before jumping off the stage into the security guards.
Also, Katie breaking up the boys' fight by shoving them into the pool. That was the beginning of the band. Why? Because if she hadn't done that, the boys probably would not have made up in time for Gustavo's meeting with the CEO of the record company, and they would have been sent back to Minnesota. Not to mention it shows just how mischievous Katie can be.
Big Time Concert, when the boys were about to save the show, Sebastian gives Hawk and Rebecca (who employed him earlier in the episode) a blast with his hot towels. Priceless.
That entire scene is one big Moment Of Awesome, really. It starts off with an intense Tear Jerker moment as the crowd begins to abandon the concert as Hawk starts to gloat as Gustavo panics, then just as he's about to faint, the boys swoop in and save him from falling. After Hawk and Rebecca's comeuppance, the boys perform their song, and it shows what looks like clips of the boys performing in real life at Times Square, and when they finish their song they stand victoriously. They are then chased out by the entire goddamn crowd. And for the record, this is coming from a troper who used to see the episode as a Wall Banger until seeing it again recently.
Kelly and Gustavo getting the better of Griffin was pretty awesome too.
For emphasis, the ending of this episode is the consummation and culmination of every single thing that happened, all of Big Time Rush's efforts during the first season. This is their dream, and they are living it, and living it awesomely, complete with Imagine Spot flashforwards to Times Square. This moment is pure unadulterated success.
The climax of Big Time Movie, the boys actually fight Atticus Moon's henchmen (bonus points because some of the henchmen where appeared to be armed with guns.) It gets kind of dark with the likely hood that some of the henchmen where killed (Carlos was using a sonic cannon, that is a pretty powerful weapon), Kendall even gets hit in the ribs by Atticus Moon's top enforcer, who had a silver hammer for a hand, and Kendall just got back up like it was nothing.
To top it off? They saved the world. That is impressive.