I have been written on using a whiteboard marker and as this was F/m this involved the penis. I tell you, it can take a while to write out the entirity of Hamlet's famous soliquily in large print down the length of a penis and not many penis's are large enough but thankfully... (yes, ok, you are not the only one who can be silly )

Seriously, had whiteboard marker (very temporary - a quick rub or some sweat will get rid of it) and lipstick on chest and penis and as stated above it is usually humiliation - 'Master's slut'. 'Mistress's cock' and so on. It is nice to hear about some none humiliation based bodywriting - especially if you use a different script (chinese or japanese lettering, runes, etc) to do it.