Protection Against Theft and Vandalism - When meeting new people and exchanging friend codes, you can never be too sure about who will be nice. Not only will some people run around destroying flowers and such, but some may go around stealing things laying around or in your house*. The only way to prevent this is to hide everything. But that's no fun, now is it If you catch someone in the act of stealing or ruining somehting in your town and see them heading for the gate in an escape attempt, either turn off your Wii, reset it, or unplug it. Not only will this prevent the person from getting away with their act, but you also don't have to deal with Resetti.
* Yes, there are some people that can steal from your house. Using a WiiChannel downloaded froim the Internet, it is possible to mess with the game's codings, allowing various things, such as stealing from houses or placing things in someone's house.
Stuck Behind Sable - In order to get stuck behind Sable, a certain situation must be created. Directly to the right of Sable, two paths separate at a 90 angle. Put one person on the far right, and one on the path going down. Have the person on the right start running towards Sable, and the person that went down go directly upward, and have the people meet up at the end of the angle (but have them continue to run) with the down person arriving at the corner just before the right person. The right person should push the down person through Sable. Sometimes the right person is also pushed through, getting him/her stuck behind Sable. The only way to get out is if two people are stuck behind Sable. It might push them both out with just that, but if it doesn't, have one person talk to Sable, and either both or one person is released. Don't do this glitch with only two people in your town because the person that is stuck will be stuck until you turn the game off.
Stuck Beneath the Museum - In order to get stuck beneath the museum, have two people meet up as close to the top of the Roost's sign as possible, then have them plit up at a 90 angle with one person going up, the other to the right. Have them both run towards the sign, the person on the right going above the sign as close to it as possible. Have the person on the right reach the sign just before the the person on the top. If done correctly, one or both of the people will get stuck beneath the museum. Once there, you're stuck and can't escape. The only way to get out is by resetting.
Also, ignore this part. 
But then I come back because I'm not that mean.