Um, just make sure you're in a safe environment, don't drive, I wouldn't mix alcohol with your night either, stay moderately hydrated as well. Did you test what you're about to consume?
Is it pill form or molly/powder? You should check this place out if it's a pill:
ALWAYS look up your pill, I don't care how much you trust the person you got it from. Just because you trust the guy YOU got it from doesn't mean you can trust the guy that HE got it from.
As for what you should do.. Well
Try spending some time on YouTube watching lightshows That's always fun. OR you could crank the music and dance around like an idiot in your room for a few hours.