Is it possible to have a fun, over-the-top evening and feel absolutely no guilt whatsoever about it the next morning?

Indeed it is, if you choose to check out a special upcoming Primus concert on Friday, May 18, at an unusually intimate venue — The Catalyst in Santa Cruz.

Because madcap bandleader Les Claypool won’t just be previewing prog-themed new material from the band’s upcoming album — he’s scheduled the exclusive show as a benefit for his nephew Matthew, one of the best possible causes to which his fans could contribute.

As we reported last Christmas, Matthew — the son of Claypool’s brother Ron — was born under a dark cloud, and diagnosed with acute lymhoblastic leukemia at only two months old.

He (and his family) now face over three years of financially crippling chemotherapy treatments to overcome the disease, so every last cent will help.

The concert is officially being presented by Ron’s company, Green Gopher Garden Supply, but any Primus faithful who can’t make it can make a heartfelt donation at www.babymatthew.org.