A FRIENDS marathon consists to watch the series FRIENDS from the start to the end. Basically, without interruption (except peeing and maybe cooking) a FRIENDS marathon consists in 10 seasons and 236 episodes (equals to 3 days, 15 hours and more than 16 minutes of happiness).
The aim of a FRIENDS marathon is to each quotations and jokes of the series. This is quiet the ultimate challenge for every FRIENDS fan.
Instead of studying for my mid-term exams, I did a FRIENDS marathon.