Ideas for cheat codes (serious and funny ones)

Funny cheat codes... hmm. Oh, I would love if you could hear the enemies chat with eachother before you engage their combat scripts. Like if they are in screen, but you aren't close enough for them to notice you they talk about hellish castle life.

Squeaky shoes like Pumpkin in Lament of Innocence?

All around: Enemies get flown all over the place when they get hit
Reverse Mode: Left is right, right is left, up is down, and down is up. For directions.

I like the annoying shoes idea
I think it would be awesome if IGA released the cheat codes once every week. People might not like that, but it would be cool to get excited over some cheat codes every week, not all at once. He should let fans vote on that.

Slippery floor: becomes more difficult to come to a halt.

More obvious and serious ones:
Max level, no level up, super speed, super jump, start with determined equipment, one-hit KO...

Upside-Down Mode: Self-explanatory.
Turbo Mode: Everything is faster.
8-bit Mode: Everything turns into 8-bit graphics
Classic Mode: Changes life, and attack system into classic Castlevania style. Like Richter in SOTN.
Weather Codes: Change the weather.
Konami Code: Triggers David Hayter's voice berating you? I don't know.

Glass Cannon - Attack Power is multiplied and enemies hit are afflicted with a bleeding status ailment, however one hit from any source of damage not including poison, will kill you.
Alien Ending - I liked these in Silent Hill. You had to do something completely off the wall to get these endings and often times they would include characters and scenarios that happened in past Silent Hill games. I just want something completely silly that resolves the story in a completely ridiculous way (i.e. aliens, little gray men, did it).

Yes! This!

Villainous Monologue Mode - Whenever Miriam encounters a boss she goes into a monologue where she gloats about her nefarious plans for the castle and how the boss simply cannot be victorious in the face of such genius before the battle begins, extra credit if she throws a wineglass at the end.
True Chaos Mode - Enemies attack each other as well as you.
Dominatrix Mode - Miriam's clothing is replaced with a tastefully done special outfit but only when she has the whip equipped.
Classic Movie Mode - Black and White game-play in which all cut scenes are replaced with old-school silent acting where characters mouth words without voice then a cue card of the dialog pops up after they finish talking.
Impatient Mode - If Miriam is left idle for too long she begins to explore the castle on her own attempting to beat the game by herself without the player.

Iga track - Activates a commentary track by IGA!
Ritual of the DAY - Makes "Ritual of the NIGHT" actually happen during the day.
Gerbil - Changes the name "Gebel" into "Gerbil" in dialogues.
Beatbox - Changes sound effects into sounds poorly made using only the mouth. (pew pew pew quality)
Most Secret Secret Ever - A code that doesn't do anything really, but will get people to spend hours trying to figure out what would it have changed.