Anonymous (3:36, 29-03-16)
I'd assume they did Rock-Paper-Scissors before becoming limbless,
however the backstory for this image feel better suited as part of that 'Pins' story elsewhere on the site:
maybe a new third bisexual roommate, due to economic reasons (rising rent prices). She eventually finds out about the pins and later is enjoying them herself. They all want to be limbless using a single holding pin, but one must remain. To avoid a repeat of certain incident from happening again.