Unmarked spoilers are ahead, per Spoilers Off rule.

Secret Vampire

Poppy dances around her kitchen in her pyjamas, singing "I"m a sex pixie". Her brother Phil, who is reading the newspaper, doesn't even look up as he flatly tells her "No, you're not".
When James and Poppy are discussing vampire traits:
Poppy: And obviously we don't have to sleep in coffins.
James: No, and we don't need native earth, either. Myself, I prefer a Sealy Posturepedic, but if you'd like some dirt ..."
After Thea lets Poppy drink some of her blood, Ash remarks that he's feeling a bit hungry too. Thea smiles sweetly and tells him to "go jump in Lake Mead".

In a moment of Black Comedy, when the Redfern sisters find their great aunt Opal lying in the basement with a stake through her chest, Rowan cries that the poor old thing must've tripped and fallen. Kestrel and Jade instantly give each other "Are you serious?" looks, as it's very obvious she was murdered.
The first time Mark meets Jade, she's dancing and singing along to a radio commercial as if it's a proper song. It's both Funny and Heartwarming, as up until this point Jade has lived her entire life on an enclave where things are pretty much run like they're still in the 17th century, so she's rather naive about the rest of the world and just having fun without fear of reprisal.
In another moment of Black Comedy, when Mary-Lynnette and Mark catch the sisters re-burying Opal and feeding from a deer, the sisters’ reaction is to be put-out more than anything else.
Mary-Lynette repeatedly kicking Ash on the shins whenever he gets on her nerves. He's a powerful and dangerous vampire who could kill her fairly easily...and she just doesn't give a crap. Ash, for his part, is mostly just annoyed whenever it happens.