Partygoers at a music festival were left shocked after an attendee wearing nothing but shoes and a backpack allegedly masturbated in front of the stage.

Footage of the troubling incident shows the man among a packed crowd believed to be at music festival Listen Out in Centennial Park in Sydney last Saturday as US rapper Ice Spice was about to perform.

Paying guests can be heard shouting insults at the naked man and telling him to leave, though he appears oblivious.

NSW Police confirmed a person attending Listen Out was charged with wilful and obscene exposure, though have not clarified it is the same man shown in the video.