Couple examples of the funny variety:
"I'm going to find her, wherever she is, tie her up, and torture her till she likes me again." - Spike
Willow (about Buffy): "Guess she's out with Riley. You know what it's like with a spanking new boyfriend."
Anya (re. Xander): "Yes, we've enjoyed spanking."
And at least this one for the sincere:
"I know you'll never love me. I know that I'm a monster. But you treat me like a man, and that's..." - Spike, words failing him for once.
I'll surely be thinking of more over the next few days. Add your own!