This is one of the Community Promotion Ads, submitted by the UX.SE site members and voted on via this site (meta.ux.stackexchange).
From the original post: Community Promotion Ads - 2012
Community Promotion Ads are community-vetted advertisements that will show up on the main site, in the right sidebar. The purpose of this question is the vetting process. Images of the advertisements are provided, and community voting will enable the advertisements to be shown.
All stackexchange sites run these promo ad suggestion events every year, and the top ones are rolled out to the main ux.stackexchange site.
As for whether or not is says 'FUX', well that's all in how you read it. ;) It was designed by Roger AttrillRoger Attrill the highest-rep user on this site (by quite a long way, I might add) so you'll have to ask him. He's in the main chat site occasionally so you can ping him a message and get him to explain himself. He's a very professional chap though, and someone as upstanding in this community as himself isn't likely to try to sneak in a swear word just for a cheap laugh.
Probably.