Update: Jerry Casale apologized on Twitter for the cake.

"Deep apologies for all offended," wrote the musician. "There is a real explanation and its not what you think. Surprise cake and pix to TMZ was a set up. TBC..."

Casale told Billboard that he had no knowledge of the cake until his friend brought it to the wedding.

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He said he and his wife got married on Sept. 11 because the Beverly Hills courthouse is only open on Fridays, and this was the last Friday available before their marriage application expired.

When one friend questioned Casale's strange choice of wedding date, Casale claims he said he and Napp "are the Twin Towers of love."

Then Casale said one friend who overheard him say that offered to take care of the cake and party favors, creating a 9/11 theme, unbeknownst to Casale. Casale said his friend is the one who chose the Twin Towers cake and the box cutter party favors.

"He thought it was some sort of transgressive sick humor, and the problem is, it's not funny," Casale said.

The singer and bassist added that he is upset that someone must have leaked the photos to TMZ -- there were only 20 people at the reception.

Deep apologies for all offended. There is a real explanation and its not what you think. Surprise cake and pix to TMZ was a set up. TBC... — Gerald Casale (@Gvc3Casale) September 15, 2015

Devo singer and bassist Jerry Casale got married on Friday, and used the anniversary of the Sept. 11 attacks as a theme for his wedding.

Casale, who wed Krista Napp at Michael's Restaurant in Santa Monica, California, included several details to highlight the theme, reports TMZ, who has photos of the event.

The couple served a wedding cake shaped like the Twin Towers with Casale and Napp's faces on each tower.

The bizarre reception also used table setting cards that featured an image of an engraved box cutter that said "Gerald & Krista" on it. Then, the guests received real box cutters as party favors. In case you forgot, one of the rumors about the 9/11 terrorist attacks was that the hijackers used box cutters to stab airline staffers and take over the planes.

But sources told TMZ that guests were not surprised by the 9/11 antics given the couple's shared dark sense of humor.

We're not sure the families and loved ones of the 2,977 killed victims of the attack will find it so funny.

One guest chalked it up to a unique artistic sensibility, telling TMZ Casale has "real heart as an artist, and is a super sweet guy."