"Molly is a slang term for MDMA, the active chemical in ecstasy, a drug often associated with electronic dance music (EDM) concerts. The crowd erupted in cheers after Madge asked the question (see video of Madonna on stage at the bottom of this article), but not everyone in the EDM community was happy."
Deadmau5 Slams Madonna Over 'Molly,' Ecstasy Reference At Ultra Music Festival
That’s disappointing to hear...didn’t think Madonna would be into that. Of course, she’s trying to stay relevant, it’s quite embarrassing.