A common phrase I’ve noticed on social media is reserved for when people arrive somewhere an announce "Melbourne/Australia/(etc.), I’m in(side) you!" A random sample of examples for you:
This phrase allows the person to declare that they are somewhere new, and exciting (and likely somewhere that their friends aren’t). It’s supposed to be a little bit smutty and a little bit silly; you sound like you’re in a bad love scene with a city/country in a trashy romance.
This post is largely observational, and not backed up by too much research, but it’s a trend I’ve been noticing on Twitter and the likely lately. I’m sure someone knows what pop culture reference started this trend.
Clearly I’m not the only person who has noticed the proliferation of this phrase. I Am In You Tweets (@IamInyouTweets) is a ready-made little corpus.
[Update: I had a lot of people suggesting that Wil Wheaton was source of this phrase. Ben Zimmer has solved this one for us though, pointing to a G+ post from Mr. Wheaton citing Kevin Smith as his source for the phrase. Ben Zimmer found a tweet from Kevin Smith where he used it way back in October 2009. Mystery solved! Thanks Ben!]