This phrase is actually a toast that originated around the fights that occurred in the pubs of old. It was commonplace for a patron to wait until his adversary was drinking from their stein of ale (and their vision was therefore blocked by the stein) to attack ... it bettered their odds of success. Tis led to the development of the glass-bottomed stein in which the drinker could keep the other patrons in their vision even when drinking.
Just some food for thought:
This phrase is actually a toast that originated around the fights that occurred in the pubs of old. It was commonplace for a patron to wait until his adversary was drinking from their stein of ale (and their vision was therefore blocked by the stein) to attack ... it bettered their odds of success. Tis led to the development of the glass-bottomed stein in which the drinker could keep the other patrons in their vision even when drinking.
Thus came the toast "Here's looking at you"