When Artie gets picked on by the students, Donkey, of all people (having been stuffed into a locker and having a "I sucketh" note planted on his butt), snaps at them, "Ya'll should be ashamed of yourselves!" Defied quickly when Lancelot says "That wasn't me." Still, having a funny talking donkey standing up against the bullies is kinda cool.
Before leaving with Shrek, Donkey, and Puss, Arthur gives a major "The Reason You Suck" Speech to his entire school and promising payback to Lancelot and his bullies.
While being stuck in Charming's twisted play, chained, and about to be gutted, what does Shrek do? Making fun of the loon, and even making his minions laugh. There's Defiant to the End, and there's mocking your captor, all with a mocking smile.
Even if it was made just to kill Shrek, the fact that the villains were able to put on such an elaborate play, with a large set, songs, and choreography, all in a matter of a few hours is pretty impressive.