What would a unique, slightly eccentric dress code be for a 21st birthday?

[Georgia Lindsay]

I need a way to describe the way I want people to dress: it's at a big country house and I want people to look smart (not necessarily jacket and tie) but slightly eccentric too.

The ideas I had were: Smart eccentric / Charity shop jacket and tie.

Any better ideas?
A bit like this but less full on:

http://www.google.co.uk/imgres?imgurl=http://cdni.condenast.co.uk/320x480/d_f/daisylowe_party25_v_29jan10_PR.jpg&imgrefurl=http://www.vogue.co.uk/celebrity-photos/100129-daisy-lowes-21st-birthday-party.aspx&usg=__79ZZdK_gGULLSXZ4Wyz-4kqE0FE=&h=480&w=320&sz=58&hl=en&start=0&zoom=1&tbnid=HHpVraf7qulFxM:&tbnh=135&tbnw=97&ei=5nheTaufAYGu8QOVj-X8Cw&prev=/images%3Fq%3Ddiasy%2Blowe%2B21st%26um%3D1%26hl%3Den%26client%3Dsafari%26rls%3Den%26biw%3D1275%26bih%3D600%26tbs%3Disch:1&um=1&itbs=1&iact=hc&vpx=133&vpy=85&dur=367&hovh=213&hovw=142&tx=68&ty=106&oei=3nheTf3QD9CHhQfP5sCvDQ&page=1&ndsp=24&ved=1t:429,r:0,s:0

http://www.google.co.uk/imgres?imgurl=http://images2.fanpop.com/image/photos/10600000/Daisy-s-21st-Birthday-Party-daisy-lowe-10620044-320-480.jpg&imgrefurl=http://www.fanpop.com/spots/daisy-lowe/images/10620044/title/daisys-21st-birthday-party-photo&usg=__EOZ-z2fBd_zhZAwxedRWm-uctOg=&h=480&w=320&sz=62&hl=en&start=25&sig2=DfxJ5eTndailHhH0GyxeNA&zoom=1&tbn