What happens to the sound when you hit a tuning fork and put it in a cupboard?

Oh, dude, when you hit a tuning fork and put it in a cupboard, the sound waves produced by the tuning fork will bounce around the enclosed space of the cupboard, creating a reverberation effect. This can make the sound seem louder and last longer due to the sound waves reflecting off the walls of the cupboard. So, like, it's basically like giving the sound a little echo chamber to hang out in for a bit.