Showing that the expansion is worth buying is the little argument Anders and Oghren can have. They mock each other culminating in this moment:
Oghren: (in a mockery of Anders' accent) "Oh no, big templar man! What are you going to do with that sword?"
Oghren: Don't play with fire unless you wanna get burned, son.
The Pony conversation with Oghren in Awakening.
Warden: I bet you can't tell me what you just said.
And let's not forget Oghren's Joining in Dragon Age: Awakening. First he asks why the goblet is so small, then drinks it. What tops the scene off is that you don't get the creepy whispering scene like with yourself and other people, he just smacks his lips and says it's not bad.
Varel's reactions are hilarious as well.
Later on, when he complains that he's gotten a strange green rash and wonders if it was something to do with the Joining, the Warden can suggest that's because you're not supposed to drink the whole goblet.
The Warden can speak with Anders about why the Templars want to catch him so badly. Anders comes up with the excuse that the Templars think he's a blood mage or something. However, if Anders is made to choose Blood Magic as a specialization, the Warden can then point out that Anders does have a reason to be chased after. Anders will laugh and reply "Well, the irony is not lost on me."
Oghren starts poking fun as Anders' robe, at which point Anders notes that the robes are functional in the, ahem, tightly regulated confines of a Circle Tower. You and a "friend" can slip off into a quiet corner and, ahem, take care of business without the Templars noticing and then get back to your routine, with none of the fuss of pants and belts. The icing on the cake is Oghren's "Really?" response.
Oghren's increasingly frustrated attempts to get Justice to tell him if... everything works. It gets to the point where he starts screaming in frustration.
In one triggered party talk, Oghren wants to talk about his darkspawn dreams.
Oghren: So, I saw a Broodmother and masses of darkspawn that neared and cornered me...and then they started to talk things like "Do you want honey in your tea?" "How's the baby?", and they asked me if I would teach them to read and write.
Warden: I think that the normal darkspawn dreams aren't quite like that.
This precious party-banter gem if you have Nathaniel and Anders in your party:
Anders: It's shameful how long it took me to come up with that.
In Awakening, when Oghren is talking about beginning the Joining.
Oghren: Now where's the big cup? I'll gargle and spit.
The Warden: You're not allowed to spit.
Oghren: (laughs) That's what I always say.
During the Awakening quest "A Daughter Ransomed", if you are playing the same character from Origins then one of the conversation options is to tell the band of kidnappers that you are the hero of Ferelden who has spilled the blood of countless before, and then everything goes to shit. Some guys run off, pretty sure at least 3 jump off a 100-foot cliff, etc.
The persuasion route has the Warden conning them into handing over the girl before they will agree to hand over the money, then pointing out their stupidity since they've just handed over their only bargaining chip. Oops. Doubles as a moment of awesome.
Velanna flipping her shit when Nathaniel calls her ears 'clownish'.
Nathaniel is a wellspring of perfect deadpan comedy, particularly in his apparent campaign to drive Velanna up the walls (which may or may not also be his way of flirting with her). For instance:
Velanna: I am simply wondering how your kind can call yourselves "nobles." It seems ironic.
Nathaniel: We like irony. And it rolls off the tongue better than "oppressors."
Velanna: Ah, so you're a funny human.
Nathaniel: Not I. I wouldn't dare lighten your mood, my lady.
Velanna: You asked me if I believed that my ancestors were once immortal.
Nathaniel: And where in that question was it implied that I believed otherwise?
Velanna: Then you do believe the elves were immortal.
Nathaniel: I didn't say that either.
Velanna: You... are... exasperating.
The following moment unfolds over five banter sequences: Oghren feeds Velanna a story about how dwarves are born from rocks - gray-streaked ones are boys, pink ones are girls. Velanna actually asks Sigrun if it's true, much to Sigrun's amusement. Sigrun then admits to Oghren that it was Actually Pretty Funny ("She was huffing like a constipated bronto!") Not to be outdone, Velanna gets her own back by giving a hungover Oghren a "remedy" that turns out to be a Hideous Hangover Cure
Queen Anora, King-Consort Cousland, Anders, and Ser Rylock out in front of Vigil's Keep:
Rylock: Your Majesty, beware! This man is a dangerous criminal!
Anora: I beg your pardon?
Anders: She means me.
King Alistair, meanwhile, thinks Rylock's talking about Oghren. "Oh, the dwarf's a bit of an arse, but I wouldn't say..."
Sigrun attempts to get Anders to demonstrate his magic by destroying a random bush. "Because it's there! It's an evil bush!" He counteroffers to entertain her with his Spicy Shimmy.
Most of the childish pranks conducted during the "Blight Orfans" questline, a fake children's charity that is (not so) secretly orchestrated by the drunk patrons of the Crown and Lion tavern.