Shhh, don’t tell a soul, but Green Day are playing a “secret show” at a charming little dive called the Tiki Bar in Costa Mesa, Calif., tonight. Considering that this gig was announced on the band’s website Tuesday and even posted on a billboard outside the venue, we’re not quite sure what makes this a secret show, but hey, who are we to argue?

It’s also being reported as Green Day’s first performance of 2011 – which is also also a questionable statement, but more on that later.

Tickets for the gig, which cost $20, were initially supposed to be available only at the door, but “overwhelming response” (when it comes to Green Day, is there any other kind?) caused the City of Costa Mesa to request a that the band hold a pre-sale. Thus, tickets go on sale at 1PM PT today, with the little detail of where to buy them expected to be announced shortly.

All proceeds will benefit the Cystic Fibrosis Foundation. “The guys from Green Day have been loyal supporters of the Cystic Fibrosis Foundation for a while now and they just totally stoked us out by throwing this secret show!!” reads an online post from the charity organization.

While the gig will be Green Day’s first scheduled concert of the year, it won’t actually be their first onstage performance. Frontman Billie Joe Armstrong and the boys surprised fans with a 10-song set back in April following the closing-night of the band's ‘American Idiot’ Broadway musical in New York. That "secret show" spanned much of the band's career, including the 'Dookie' classic "Welcome to Paradise."