Bodywriting - lots of it. Write very dirty, humiliating things all over your body as well as pictures of cocks, tits, etc. Of course, focus on what you find most embarrassing but some suggestions are - cum slut, fuck toy, cheap whore, cock sucker, pussy licker, etc.
For extra humiliation, go out in public with it still on wearing clothes that just barely cover or hide the markings. Or for real fun, wear something where the writings are visible if someone looks close enough.