To put this one in perspective: Harry was in the Nevernever, the world of the Fae, about to take part in a battle that LITERALLY held the balance of the entire world at stake... and he has the cajones to say that. Crazy Awesome to the EXTREME.
For those unfamiliar with Peter Pan, in that work a fairy dies when you stop believing in them.
"FOR THE PIZZA LORD! CHARGE!"
Harry getting the Unravelling from Aurora and yelling "meep meep!" before running off.
Harry's response to Maeve's ham-handed, but magically enhanced, attempts at seduction by unzipping his fly and pouring a jar of ice cold water directly onto his crotch.
Harry telling Murphy that she will be fine and if not...
Harry: Then I will personally make fun of you every day for the rest of your life. I will call you sissy girl in front of everyone you know, tie frilly aprons on your car, and lurk in the parking lot at CPD and whistle and tell you to shake it, baby. Every. Single. Day. Murphy: You do realize I'm holding a gun, right?
All of the many Shakespearean shout-outs.
"Spenser never mentions that the Faerie Queen has a great ass. So I notice these things. So sue me."
When Harry follows Fix, Ace, and Meryl into the alley outside the funeral, he gets his ass beat to the point that he can't speak clearly. When he tries to assure the panicking changelings that he's not there to cause trouble, his gibberish causes Fix to flip out and yell "He's casting on us!" Cue Meryl chucking Harry into a dumpster.
Harry taking the habit of using Exact Words when dealing with Faeries too far.
Lea: Give me your hand, child. Harry: I need my hand, Godmother. Both of them.
The Running Gag of Harry needing a haircut. Especially when it culminates during Harry's meeting with Lea.
Lea: And consider a haircut. You look like a dandelion.