These guys are unlocked by default, congratulations!

Found in the Tiki Resort level, inside behind the reception desk. Exhaust his dialog and down the drink he offers you.

Unlocks after you poison him in the restaurant, part of the story.

Unlocked by completing the credits level.

Found in the Tiki Resort level, behind the reception building. Activate her fruit ninja mini game by interacting with the fruit bowl on the bar.

Found in the Consulate level, just exhaust his dialog to unlock him.

Unlocked in the Tiki Resort Night level, under the covered pool after completing his dialog.

Found in the Bachelor Pad, in the section with the gravy racing. Eat all the snacks on his plate and you'll throw them back up and unlock him.

If you've already completed the level, and don't have access to the roof anymore, you can activate the console with the tilde key (~), type in "noclip" without the quotations and then fly over to the rooftop you need to get to. To turn off noclip, type "clip" into the console.

Unlocked by completing the Matrix Hiest mini-game in the Ikayaki Alley level. The machine can be found in one of the side alleys.

Found in the Tiki Resort level, just talk to the first Tourist you see at the beginning of the level and exhaust his dialog. It can probably be done by talking to any of them, I just tested it on him.

Found at the back of the Tiki Resort level, near the outside bar.

Found in the end area of the Ikayaki Alley level where the restaurant is. Exhaust his dialog to unlock him.

Unlocked by completing the Matrix Hiest mini-game in the Ikayaki Alley level. The machine can be found in one of the side alleys.

Talk to him and he'll ask you to find the McGuffin. Go and find a goon in a side alley and he'll tell you to find the mailbox with chalk on it. It's the one near the theatre with the line. Grab the package and take it back to him. Sit on the bench and it should unlock him.

Esperanto can be found in the Tiki Resort level, to the left of the guest building elevator. Exhaust his dialog and cover him in cheese to unlock him. It doesn't even matter if you hit him with the cheese or not, he'll be happy either way.

At the end of the Bachelor Pad level you will be able to interact with her stuck in a blob of jelly. Eat her out (ha) to save her.

So you're feeling lazy hey? Look no further. Click here[drive.google.com] to download a registry file that will unlock all the Wedding Cake characters and levels for you. Can't say I blame you, I wish I'd had this file to start with.
You'll probably need to be an administrator in order to import the file into your registry.