Five Rules of Foursquare

I'm not gonna lie, I love foursquare. I've been waiting for an online networking site whose network was based on geography and location rather than solely social connections.

For those of you who live in a cave, foursquare is a mobile app that allows the user to "check in" at "venues", anywhere from liquor stores to baseball games, airports to restaurants.

As great as it is, there is plenty of room for the app to be abused. After searching for the official bros icing bros rules and foursquare rules to no avail, I thought I'd put together a few of my own rules of foursquare etiquette.

Rule 1 : No checking in at work - enough said.
Rule 2 : No more than two check-ins per day at any location - foursquare will let you do this, but I think its cheesy.
Rule 3 : When choosing a venue from a list of duplicates ALWAYS go with the one with the most accurate and complete information.
Rule 4 : No Facebook foursquare spamming - Foursquare has great facebook integration but users need to exercise caution if they are updating their facebook status every time they check-in. My rule - if you really want to TELL people where you are, update facebook but if you don't have a real reason, stick to your foursquare network.
Rule 5 : No retroactive check-ins - If you forgot, you missed your chance.

Do you have any other rules suggestions? What do your foursquare friends do that annoys you?