Please don't get me wrong - it's not like I gasped, acted shocked and appalled and then let the conversation drop. We talked, and I asked her not to do that...
Okay, good. Your OP didn't say you had, and we are often surprised how often folks look for a game-implementation solution, when simply talking to the player is the most effective way to go.
Even so, I like the bribery idea. Consenting adults, indeed.
Or, you know, she could get your favorite cookies, or something
I think it needs to be a bit more specific. Metagaming is the use of out-of-game information to affect in-game decisions, not just impact the game.
"My character will/won't do <X> because <out-of-game info>."
If X = "engage the NPC in combat" and Info = "I peeked and know the enemy's got a powerful statblock", it is metagaming.
If X= "engage the NPC in conversation" and Info = "the bard's player's been bored lately, and ought to be given some spotlight time", it is still metagaming. What my character chooses to do in-game changes based upon out-of-game information.
I resist redefining a term just so I can then make a tautological general statement - this will tend to lead to difficulties with edge cases which may not be so black-and-white. If we just go with a blanket "metagaming is bad", we skip over *why* it is bad. That's the important bit - the effect the activity has on the game experience. I don't want to abstract away from that "why" with a general principle. Addressing the "why" is most important in discussions within diverse gaming communities, where people play many different games in different styles. What's bad for your game may not be bad for mine, so generalizing is probably not the best idea.
Plus, just linguistically, the term "metagaming" is a construct based on the meaning of the prefix "meta-". You suggest restricting "metagaming" more strongly than is indicated by the prefix. So, what should pop to mind when the word is seen, and what it actually means, won't match. That's a recipe for confusion.
How so? Isn't this just following the rules?
Sometimes, a game will have a rule that enforces genre, but often they don't.
Take, for example, GURPS - a game that is supposed to be generic, and therefore has few rules to enforce specific genre. Say you're playing GURPS, and the game is supposed to be a prohibition-era gumshoe detective game. The Lady In Distress comes to the PIs office, and sets him on the case. The PI's player has a choice - he could have his character go to the local mob-speakeasy to dig for clues, or he could just have the character pick up a rifle and attempt to assassinate the person the Lady In Distress says is a problem.
No game rule prevents either action. However, the first is in-genre, the second is out-of-genre. Choosing to do the in-genre thing *because* it is in-genre, is a metagaming decision.
