Richard suggested that people turn up wearing tuxes and hawaiian shirts, as a tribute to our office manager who's headed back stateside. Then he backed down to "a nice suit and a hawaiian shirt". In the end, we had Richard in a pinstriped black velvet suit and hawaiian shirt:
and yours truly in a regular suit with a non-Hawaiian, but the best I could manage at short notice, shirt and paisley-patterned tie.
Oh, and a santa hat (the one that's in front of Richard).