Yes, I like to think I have this Key. So what?

Key of "You think you know me?" 
It happens all the time. Some player sitting 'round the table says to you: "Oh, man, and now you're so going to tag your Key of [Something] again because of this! Easy money!" (or variations). But in fact you…
1 XP = Can't tag your Key of Something, because it doesn't apply.
2 XPs= Don't have the Key of Something at all.
5 XPs= Can and do buy off your Key of Something right now.
Buyoff: They're right, your Key of Something applies and you tag it for 3 XPs or more.