A pornographic magazine typically with photographic images of naked ladies found new on the top shelf of newsagents managed by broad minded retailers or found second hand in waste ground. Phrase was mostly used by teenage boys in 1980s when speaking of said genre of magazine or also be used as a term to chastise their friends. The term is of Glaswegian origin and perhaps used exclusively in Scotland.

When you eat dirt for the first time and leave your family to build a shack in the woods

To facebook in the nude, as in bare ass naked. This often happens after one gets out of the shower and decideds to check facebook before getting dressed. It can also happen any time of the day in which one decides to be naked while at one's computer.