those things are great. we played a joke on my brother with the ones that are a part of the reverse light bulb(really loud), we put it on his new Lexus without him knowing, sounded like a forklift backing up....he was like "
WTF!!!!!!" every time he backed up. he thought something was broken and took it to the dealership after like 3 weeks of being pointed and laughed at in parking lots.
best part, lexus techs acused him of putting it in(not covered under warranty) and wanted to charge him an hour of troubleshooting when it really took them like 5 min! he didn't end up paying anything though.