The fifth annual Virgin Mobile FreeFest brought a swarm of over 50,000 fans clutching rain jackets and umbrellas to Merriweather Post Pavilion for 20 performances across three stages Saturday.

Concertgoers trekked through muddied grounds and artists lightened the mood by jesting with the crowd. When Swedish duo Icona Pop closed their set with their raucous electro-pop single “I Don’t Care,” they jokingly inviting fans to join them for drinks afterwards.

Psychedelic indie group MGMT riled casual fans when it omitted the well-known “Kids” from their set list, but awarded one audience member a temporary position in the band. A woman from the audience was brought on stage to play the cowbell during “Your Life is a Lie.”

Pop crooner Robin Thicke teased audiences through a set of obscure, older tracks, holding off on his polarizing hit “Blurred Lines” until the very end of his set. Some artists welcomed the stormy weather, incorporating the rain into their sets: Electronic solo artist Pretty Lights used the showers to enhance his light show, sending glittering, multi-colored rays across the neon-wearing crowd of the Dance Forest.

Virgin Mobile has partnered with the nonprofit for at-risk youths, Sasha Bruce Youthwork, since 2009 to hold the free annual concert.

This year’s donations will fund amenities and programming for the eight homeless youths who live in the RE*Generation House in Southeast D.C.