Evelyn, Evelyn: Klance

Childhood friends, Lance and Keith, volunteer for a scientific experiment. The experiment fails, ending with them being conjoined at the shoulder and the hip. The scientists gave them the chance to be severed, free of charge, but the boys decided to stay conjoined. To them, it just meant they would be friends forever and do everything together.
Right?

Based off the song Evelyn, Evelyn by Evelyn, Evelyn