It’s a special kind of household appliance which Brazilians are very proud of: electric showers. They were invented in Brazil in the 1930s and are today found in many of the South American countries.
I often feel that they are not really meant to heat the water but to make it less cold. However, on occasion, they come with a special ‘wake-up’ service: jolts of electricity. Depending on the installation, a bit of alternating current really gets you out of the sleepy mood and right into an annoyed one; ready for shouting that this is a hazard that one day might kill someone.
So, long story short: while electric showers actually do their job well, you are advised to do a little safety check before stepping into one of them.