The first was the dutch guys (who went on to start TheNextWeb) showing up at the house randomly early in the morning (we weren't morning people) after finding the address online. I was woken up by them since my room was at the front. They bought over coffee, I thought they had been invited so let them in. They stood around for 30 seconds then all charged into Arrington's room and woke him up. He had no idea who they even were, took him 20 minutes to get his bearings and to figure out who these guys were. What made it weirder and surreal like a von Trier film was that these guys all looked similar and were dressed in matching white suits - when I first saw them they were actually walking through the back yard. Having just woken up to a sound of people walking around the house and seeing three blonde guys with dutch accents in white suits trampling through the backyard carrying Starbucks and donuts, I really thought I was tripping.

This story was told in the opening of the Wired profile:

http://archive.wired.com/techbiz/people/magazine/15-07/ff_ar...

As much as we tried to scrub the address online so people wouldn't show up, it was useless. Foursquare was a nightmare because people would come over and then 'check in', giving away the address of where we lived to the world without thinking about it

Second time was in Vegas. Arrington finally unplugged and took some time off and we made a last minute trip to vegas. First day there, get to the pool, have a couple of drinks and he takes a photo of the view looking up at the sun and uploads it to flickr (iirc). 3 hours later back at his room and the room phone rings - I hear one end of the conversation - "yep, uha.. uha.. you know, this is really inappropriate.. you're not doing yourself any favors.. don't call again". Gets off, and it turns out someone had tracked the GPS coordinates in the exif embedded in the photo, worked out what hotel we were staying at and called the front desk asking for Arrington, saying they were a friend. They got Arrington on the phone and then spent 30 seconds blurting out their startup pitch. They also thought it was a cool hack, but it was just very very creepy. Made that entire day very uncomfortable and it rattled Arrington for a while. We ended up changing all of our names with the hotel after telling them about it and they set us all up with aliases (which is something they apparently do as a security measure for celebrities, politicians, or people looking for privacy etc.)

edit: privacy violations affect people, it is really fucked up - have respect for the personal space of others.