I used to slip inside jokes into my books all the time. Some of them were specific to one person, some of them were specific to a group of people. To use some examples, in Through a Crimson Veil The Crimson Jim bar was named for a guy I worked with. He's also the one that asked me to use Evil Twin Brewery in the story. That's the brand of beer Conor was drinking the night he found out the truth about Mika.
The inside joke in Eternal Nights was out there for any baseball fan. All the one-off secondary characters, the ones that were basically walk-ons, but who needed a name for clarity's sake, got the name of baseball players. Wyatt's friend in the prologue is Jim "Catfish" Hunter who is like a totally famous pitcher from a few decades ago. All the bad guys got names of players on teams I was rooting against in the playoffs that year. (I was writing the book during the playoffs.) Only one person ever let me know they got the joke and this kind of made me sad. I was hoping a lot of people would get it and laugh with me.
But EN was the last book that I did anything sort of under the radar. Kind of. If you read Shadow's Caress, you'll remember it opened with a couple of 80s songs and it also closed with the title of an 80s song. But stuck in the middle is a little tip of the cap to another 80s song. I originally was actually going to name the song, but it didn't work out with the flow of the story.
I did make a reference to it, though. When Malachi has Cass pull over and tells her they're going to walk the rest of the way to Laurent's home, Cass is like: What? Walk? In LA?
Maybe no one else gets it because Missing Persons was never a huge name group, but they have a song titled Walking In L.A. and the whole thing is about how nobody walks in the city. Since Cass works in an 80s boutique, I thought it was kind of fun to slip in something like that. I just wish I could have managed a few more songs.
