They should smoke weed if they haven't already. They will freak out doing stims, and might even freak out from weed alone if they've never done any drugs before. If they've seriously never done anything before, you guys should just roll up a couple joints, grab a case of beer and have a fun night.

I think Molly is just about the worst choice. It lasts much longer than coke, and I think even the comedown is worse. Coke is also awful first drug also because of how fiendy it is. A good night of coke requires constant redosing, and is almost always accompanied by a lot of alcohol, which is an uncomfortable situation for people who aren't comfortable around drug use. But if they're heavy drinkers they'll definitely enjoy boozing, doing blow, and talking about everything.