Nope, not 'double rope skipping', how to wriggle in under the Playground fence or even where the wine cache is hidden. It was how to make backgrounds like this:
Give up? It's so easy, when you know how:
Take one alcohol ink pen (Copics, Pro Marker etc), find a Bic or similar ballpoint pen and remove the top stopper, pop out the ink barrel and you're left with a clear tube. Len had to drill the top stopper out of this pen, in the old days they used to just pop out but I bet Elf an' Safety have decreed they must be glued in!
Then just clear a bit of space, grab suitable card/paper, put the narrower end of the pen tube really close to the fat nib of the marker pen - and blow down the tube :) I don't mean a dainty little 'wuff' either, put it into your mouth and 'gie it a good bla' as they would say in Scotland. The harder you blow the heavier the 'ink spattering' is. Fun huh? Of course you can buy cans of aerosol air to achieve the same but it's a cheap and easy tip. Apparently it doesn't work well with a straw - I think you need the narrower end to get enough air pressure against the nib.