What happens when you get no sleep, but you take melatonin to make you sleepier?

I didn't do this, I heard my friends talking about it. They said it's like being 'high' because you're so tired, & taking melatonin adds more of an effect. I will repeat, I'm not going to try this. But what they'll do is like go two days without sleeping, & take three melatonin & force themselves to stay awake. What happens when you do this?