I did...
1) euphemisms and political correctness eg. Saying 'differently abled' instead of 'disabled' and chairperson/actor instead of chairman and actress etc
2) taboos in certain contexts eg. using the dysphemism 'ranga' in a casual, private context vs. NSW politician calling Julia Gillard a 'ranga'
3) how social values differ between societies and thus what isn't taboo in Australia may be offensive in the UK(eg. where the bloody hell are ya?' and USA(eg. Aussie 'Spicks and Specks' iPhone getting censored in America due to the culture differences that change semantic content as 'spick' is a derogatory term for a hispanic.
Yeah the 2 subsystems thing was lame. But i did lexis(of course), morphology and semantics