Why does my dog like a shower?

Not once, not twice, not three times, but four times my border collie was left alone and turned on the bathroom shower. each time we returned home, he was standing in the shower enjoying the cold water over his body. he was soaked from his nose to his tail. why does he do this? my dogs name is Mikey and we now call him Psychi Mikey. does your dog exhibit such strange behavior? if so, i need your assistance in trying to figure out why he does this and what to do to prevent this in the future?