Andrew McMahon of Jack’s Mannequin danced on top of his coal-painted Baldwin piano wearing a grass skirt, a coconut bra and a flower lei on Halloween night as the band performed at the House of Blues in San Diego.

“I’ve been waiting a long time to wear a bra on stage,” McMahon said as he thanked the audience for coming out to the show.

The show opened as he belted out the lyrics to “Spinning,” with a soothing passion from deep inside his voice: “I can’t remember when the earth turned slowly.”

His energy was right at the level of his college-age audience, many who came out dressed in their costumes. The scene looked much like the “Peanuts” cartoon, “It’s the Great Pumpkin, Charlie Brown” with the crowd and band wearing various costumes and McMahon, instead of Schroeder, on the piano. All that was missing was Charlie Brown’s ghost with one too many holes.

The show went until the early evening, leaving plenty of time for partying afterward.

As McMahon introduced the song “Swim,” about doing whatever it takes to find goodness in life, the crowd buzzed with excitement. Before diving into the piano keys with his passionate and expressive playing style, he addressed the audience:

“This song is about keeping your head above water,” he said. “Sometimes it’s something you need.”

The tour promotes the band’s second album, “The Glass Passenger,” which was released on Sept. 30 of this year. It comes three years after McMahon’s struggle with cancer.

McMahon was diagnosed with leukemia two months before Jack’s Mannequin’s first album, “Everything in Transit,” was released. Songs such as “Dark Blue” and “The Mixed Tape” were brighter days compared to the darker lyrics of “The Glass Passenger,” which tell the story of his pain. It’s also his journey to the surface from beneath his past, which he tells in his documentary, “Dear Jack.”

His earlier style in the former band Something Corporate resembled that of Ben Folds on the piano, but this tone is anything but pop. His songs make a strong connection to his audience.

Julie Katsnelson, a college student at University of California Irvine, has been listening to the band for six years. She is such a big fan that she will travel several miles for shows. She has already seen the group perform four times in October.

“It’s a combo of what he sings about,” Katsnelson said. “It’s about his survival … you hear his pain, his struggle and resolution…he feels every note he plays. It’s amazing.”

McMahon spends much of his time giving back and raising awareness about leukemia through the Dear Jack Foundation, www.dearjackfoundation.com, a nonprofit charity that he founded in July 2006 to assist efforts leading to advances in a cure for blood cancers and to offer support to young adults.

On his MySpace page, www.myspace.com/jacksmannequin, McMahon writes a personal thank-you letter to all those who contributed to the Jack’s Mannequin National Light the Night Team, which raised $100,000 for the Leukemia and Lymphoma Society. He writes, “I am most certainly in awe…”

It is evident that McMahon values life and uses his platform as an artist to give back to those who are facing the same darkness he once did.