He was probably just drunk and wanted to listen to music, and didn't intend on robbing you.
I give people dollars all the time. Its an unexpected but pleasant way to show appreciation for little things (such as lending your headphones), or to cheer somebody up. usually works but in your case I understand why it didn't.
You probably weren't in danger, except maybe accidental injury by being fallen on by a drunk guy.
Oh wait, i totally missed the part about their pants sagging to their knees. my bad. i take it back, they WERE trying to break it off in you.
The headphones, if I read the OP correctly, weren't willingly "lent out" nor were they returned to her. This was a robbery by intimidation.
It was the actions
of the men that made it a robbery, not their mode of dress - though you could argue that the stigma associated with young men in that style of dress helped a bit with the intimidation. I don't like that line of thought because it opens the victim up to spurious and baseless charges of prejudice, ie "you wouldn't be scared of a man in Dockers asking you for your headphones" etc.
Not everyone in droopy pants acts like a criminal or a robber, so it's unfair to criticize their clothing. Their actions
, on the other hand, were clearly criminal and it's completely fair to judge them for their actions.
To describe the episode as a voluntary lending out of the OP's property is breathtakingly disingenuous or naive, IMO. I don't know how much actual danger the OP was in - probably not much, but who knows? - but she was clearly deprived of property by force or intimidation. That's a robbery.