+1, funny -- but for the sake of non-native English speakers, FTR, it's pronounced the same as "psych" and is colloquial for a sarcastic "ha-ha, just kidding"
For additional cultural context, I think this usage was popularized by Eddie Murphy in Delirious (NSFW language: https://youtu.be/Ft4kEk5CHrE, you'll want to listen to at least 2:15)
Given that Eddie is telling a story from his youth it's probably fair to say it was in common use 10+ years earlier - which is consistent with my vernacular at the time.
Further, "sike" has become a common spelling when used to indicate "not really." At least, according to urban dictionary and other online dictionaries.
If you're going to address non-native English speakers, using acronyms like FTR (I suppose that refers to for-the-record, but one can never be sure on the Internet... could easily be something like for-the-retarded in some circles) may not be the best idea, BTW (by the way :D).
