What's up with all the yellow smiley face signs popping up around Grand Rapids and the Lakeshore?

No one seems to know for sure, since whoever is behind the "Get a Smile for the next big thing for GR" guerrilla marketing campaign isn't talking.

There's no way to tell if it's all a bunch of hype, but the signs are gaining notice and prompting speculation that a "big announcement" is coming Thursday.

Some have speculated Thursday's announcement is about a big event or change coming to cancer support group Gilda's Club Grand Rapids. Calls to and emails sent to President/CEO Leann Arkema and Community Relations Director Wendy Wigger were not returned.

The signs are cropping up along roadsides, outside downtown merchants, and even on the ArtPrize finalist "Steam Pig Experiment" outside the B.O.B.

Emails with a smiley face image attached also are circulating, and folks are being encouraged to pass it along and use it as their online avatar on social networking sites Facebook and Twitter. There's even a "#GRRSmiles" hash tag on Twitter.

"Eager to know what: #GRRSmiles is all about. Guess that makes it an effective campaign!! Such a sucker I am!" Grand Rapids Foundation President Diana Sieger wrote on Twitter.

The tag may have the "GRR" airport code for Gerald R. Ford International Airport, but Spokesman Bruce Schedlbauer said they're not behind it.

"It's not us," Schedlbauer said. "I guess we'll find out on Thursday like everybody else."

The campaign also has nothing to do with "Experience Grand Rapids" the former Grand Rapids/Kent County Convention and Visitors Bureau.

"We're not behind it," said spokeswoman Kate Wiltzer. "We were actually wondering ourselves."

E-mail Kyla King: kking@grpress.com and follow her on Twitter at twitter.com/KYLking