One of my favorites is Spike making fun of Angel during, or right after he saves some chick (I had to dig up the dialogue):
[Angel has just saved Rachel from a violently abusive boyfriend, while Spike watches — and narrates — from the rooftop.]
Spike [as Rachel, falsetto]: How can I thank you, you mysterious, black-clad, hunk of a night thing?
Spike [as Angel, basso]: No need, little lady, your tears of gratitude are enough for me. You see, I was once a bad-ass vampire, but love and a pesky curse defanged me. Now I'm just a big, fluffy puppy with bad teeth. [Rachel sways closer to Angel; he steps back, warding her off with his hands.] No, not the hair! Never the hair!
Spike [as Rachel]: But there must be some way I can show my appreciation.
Spike [as Angel]: No, helping those in need's my job. And working up a load of sexual tension and prancing away like a magnificent poof is truly thanks enough!
Spike [as Rachel]: I understand. I have a nephew who's gay, so...
Spike [as Angel]: Ah. Say no more. Evil's still afoot ... and I'm almost out of that nancy-boy hair gel that I like so much. Quickly! To the Angelmobile — AWAY!
LOL Spike