"Blue Sky" (also known as Big Blue, Blue Magic, or Fring's Blue1) is the street name which has been coined for the notoriously potent and 99.1% chemically pure crystal methamphetamine manufactured by Walter White and Jesse Pinkman.
Refers to the way that you end up doing things after consuming alcohol that do not seem to belong to your normal repertoire of behaviours. Drinking outside of the box.