gotcha.

I understand you or what you said.

Gotcha! You just want me to stay here for now.

I got you by surprise (indicating a successful trick or prank).

Gotcha! You never noticed the whoopie cushion!

I caught (uncovered) you (as when successfully bringing someone to reckoning or effecting some form of retribution).

Gotcha! What do you think you're doing, sneaking around in here?

I have caught you (literally, physically) (said by a speaker who has physically caught someone or something that was falling).

Gotcha!

I have got you covered, I've got your back (said by a speaker who has an advantage or responsibility over someone).

Gotcha! Go on in...

A potential problem or source of trouble.

Review the work thoroughly and make sure there are no gotchas.

A potential problem or source of trouble. A feature of a system or a program that works in the way it is documented but is counter-intuitive and almost invites mistake or non-function.

An instance of publicly tricking someone or exposing them to ridicule, especially by means of an elaborate deception.

gotcha question

They change the number at random intervals and if you miss a sign. What a gotcha!

An attempt to disprove or refute someone's argument, usually (but not necessarily) in a deceptive or disingenuous way.

You're asking me a ridiculous hypothetical question that no one can reasonably answer. You need to stop with your gotchas.

The gotcha in your second paragraph needs more developing. You don't have enough evidence that the author is contradicting himself.

An instance of accomplishing a tricky idea or overcoming a difficult obstacle.

Now here's another few gotchas that you can do to implement it.

Wireless was the first gotcha when installing the distro.

Pronunciation spelling of got you.

I gotcha now, ya little twerp.

Yeah, I gotcha. Good thinkin'!