A misused phrase uttered by kids who are uneducated with drugs. Molly being "popped" is not possible. Molly is the pure form of ectasy and can only be snorted. The only way you can "pop molly" is by taking ecstasy in pill form which are called "rolls". Rolls are cut with many other drugs. So when kids say "popping molly", they are completely illiterate.
Rave kid: I'm thinking I want to pop mollys tonight bro."
Rave adult: "Popping mollys? How? Don't you mean you're gonna take rolls?"
Rave kid: "Wait...uh...what?"
Rave adult: *Facepalm*
Putting molly; the pure form of ecstasy; in a pill and taking it.
Mollys being "popped" was never popular until about 2012. Before that, the drug was usually snorted up your nose.
Young Yuppie: I'm gonna pop mollys and go to a Dubstep concert tonight!
Old Hippy: What's this fancy "molly" you speak of?