A word that describes telling someone you are not going to tell them something but inadvertently telling them

Question

For example:

Me: So what do you do for a living?

Guy: I'm a fish and game warden.

Me: Interesting. Well I guess I better not tell you about all the salmon I caught yesterday.

I was thinking sarcasm but I'm fishing for another word.

Answer 1

If you're inadvertently telling them, I think the word is a blunder:

a foolish tactless remark

or a gaffe:

a social blunder, esp a tactless remark

or simple a slip of the tongue (often also referred to as a slip-up):

an unintentional utterance; a mistake in speaking.

Answer 2

The rhetorical device goes by several names. Paralipsis is one of them.

paralipsis noun Rhetoric [mass noun] The device of giving emphasis by professing to say little or nothing of a subject, as in not to mention their unpaid debts of several millions. - ODO

Here are a few more:

Apophasis is a rhetorical device wherein the speaker or writer brings up a subject by either denying it, or denying that it should be brought up. Accordingly, it can be seen as a rhetorical relative of irony.

The device is also called paralipsis (παράλειψις) – also spelled paraleipsis or paralepsis – or occupatio, and known also as praeteritio, preterition, antiphrasis (ἀντίφρασις), or parasiopesis (παρασιώπησις).

- wikipedia

Answer 3

If you accidentally reveal a bit of your strategy or intentions, it is called tipping your hand (as in, accidentally showing your cards during a game.)