I had heard of this app awhile ago when someone was telling me how they annoyed their friend with it but I never knew exactly what it was until recently. "Where's My Droid" is an app designed to help you find your Android phone if it is lost.
The main idea is that you send a text message to your phone from another phone if it is missing say, under a pile of clothes. It will ring and vibrate regardless of whether your phone is on silent, which is a huge deal for some who tend to lose their phone. Personally, I rarely do.
There are many settings to choose from and many custom options including the ability to change the keyword for your phone. By default, if you text the phrase "Wheres My Droid" to your phone, your selected ringtone will ring at full volume, regardless of your volume settings. As mentioned before, people who know your keyword can annoy you by texting you the keyword when you are not expecting it, such as when you are in class or sleeping, so it is best to change the keyword to a more personal and secret phrase.
It is free so check it out. Also you might want to test it first to make sure it does work. I would give this app a 4/5 for usefulness but as I mentioned, I would not use it very much. Thoughts and comments can go in the comment section. I have been busy lately so I have no made to many posts but I hope you enjoyed reading this and have a great day.