luma 8.0 and later has a built in feature for that just hit L Down and select all at once then select screenshot(slow) though this will not work with non 3ds games as in ds/dslite/dsi games because it unloads luma when booting
You could also use NTR CFW. I think the latest version is 3.6, and I use BootNTR Selector 2.9 to load it. Then press X+Y during the game to get a similar menu.
NTR takes screenshots a lot faster than Rosalina, but it doesn't take both images from the top screen when you have 3D turned on.
While I know you mean in case of someone confusing schooling establishment from shooting establishment (many of the same letters) I am still going to read that as lockdown (also known as lock in) for a pub
being drunk in school was either because drunk on playing field or could not be arsed with one particular Thursday afternoon so went and had some beers and played some games instead before returning for an ill advised last lesson/period