Kind of embarrassed to ask this question, but what is an angle shoot? Can you do this online too?

Its abusing / bending the rules without actually breaking them I believe. Its regarded as unethical at least.

Just google it to see some examples in live games. Online: Leaving a cashgame table when you double up and returning shortly after (tho a lot of sites don't allow that these days), abusing the disconnect protect on a site (when you want to go to showdown but not risk you're complete stack, there have been cases where people just pull the plug on sites with disconnect protect) and perhaps also using your complete timebank near the bubble of a sattelite or something.

It's more commonly used when you try to invoke the letter of the law to the disadvantage of someone who was obeying the spirit of them. An example would be if you bet allin on the river heads up, your opponent instantly flips up the nuts and says "I call", and you try to bust him on a rule that says hands are dead if intentionally revealed before showdown. While you're correct on the letter of the law, the rule is in place for reasons that have nothing to do with the circumstances of this hand. It's obvious your opponent was always calling, so trying to invoke the rule is simply trying to steal a pot which is not yours.

These have other, more specific names. #1 is "ratholing", #2 is "allin abuse" or "disconnect abuse".

Here's a good recent example: http://forumserver.twoplustwo.com/27...abling-418439/

The guy has KT high, but instead calls out "straight". The other guy, taking it for granted that the guy wasn't lying, goes ahead to muck his card, and would have had his pot cheated/tricked from him if not for the OP shouting out that he didn't actually have a straight.

Attempting to exploit any loophole in the rules or the enforcement of the rules in a way that goes against the spirit of the game.