Like Ouija boards, radio-station concerts bring people into physical contact with the disembodied voices that recurrently croon at their bedsides. Groove to some supernatural beats with today’s GrouponLive deal: for $17, you get one general-admission lawn ticket to the KCNN FM100 Birthday Bash at Waikiki Shell on Friday, July 29, at 5:30 p.m. (a $30 value before fees, or up to a $38.10 value online, including all Ticketmaster fees).

The KCNN FM100 Birthday Bash sets its sights on the fairgrounds of Waikiki Shell for a feel-good festival of reggae, hip-hop, and island pop. As this year’s Bash marks the station's 21st birthday, a prudent lineup loaded with local and international stars stands ready to escort the station through an evening of enticements. New Zealand reggae group Katchafire sets off overhead sprinklers with a rhythmic blaze of keyboards and guitars, and local islanders Kapena represent both sides of 21 with an eclectic, multigenerational ensemble of musicians. J Boog’s velvety voice spreads across the lawn like butter on a dinner roll as crowds load their plates with a bass-heavy buffet that also features Rebel Souljahz, Kendra, and Kawao.

Donated by a monstrous hermit crab with a passion for the arts, the Waikiki Shell showers audiences with a rainbow of pitch-perfect resonances. Although no outside food or beverages are allowed inside the event grounds, concertgoers are free to bring backrests and groundcovers to keep themselves comfortable and act as handy camouflage for magic carpets.