Scrawled little arrows in different coloured chalk... and maybe the occasional suggestive limerick, as well.
I remember pirating it like 20 years ago. I doubt it's changed much since then.
Madness string 1171
This is further proof that it's a DANG shame that Hasbro is not bringing back unpunched cards to the Vintage Collection despite the fact that they are shipping unpunched Marvel Retro Collection figures. Unpunched Vintage Collection cards would definitely create more of a buying frenzy than kitsch paint jobs.