Personally, I use mGBA simply because of the fact that it still receives updates. It is also pretty fast and more stable than both GameYob and Retroarch. I also uses it because it plays GB/GBC/GBA games.
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