Will anesthesia and laughing gas make me tell secrets? or make me say weird things?

When gas anesthesia is used it is administered by placing a mask over the mouth and nose so no speech can occur. some Iv anesthesia can very briefly cuse some mostly unintelligible utterances

You will be so worried about your possible pain, that you want to feel relaxed and sleepy. Secrets are the last thing on your mind.

For the most part that's Hollywood hype. If you do stay anything it's bound by doctor privilege. You do not want to have surgery without the appropriate anesthesia, so what choice is there? If your doctor(s) is recommending surgery, you should strongly considers/he recommendation.

Probably not. The anesthesia may disassociate you from your surroundings by not make you so loopy that you spill your deepest secrets.