We've all seen those videos where someone is dragged onto a terrifying roller-coaster by their cruel friend, who laughs throughout the ride at their pal’s terror.
But those clips could soon be a thing of the past, as a Dutch designer has now invented a ride that changes speed based on how scared you are.
Daniel de Bruin has designed a number of clever contraptions over the years, but the Neurotransmitter 3000 could be his finest work yet.
The person in the roller-coaster chair is hooked up to a load of neuro-transmitters, which reveal how scared the person is.
Judging on their heart rate and muscle tension, the ride then increases pace to make the person more scared.
The ride starts slowly, then picks up pace, and if you start to get a little bit comfortable, it goes even faster.
The machine also has a top speed for when the person’s heart rate reaches 130bpm — so the scaredy cats among us should have a fairly easy ride compared to the show-offs.
While the ride is still in the very early stages, the machinery could have a huge effect on theme parks in the future, with rides tailored to suit each individual person.