Normally it means there is less mixers than alcohol. A Virgin Mary (A Bloody Mary with no Alcohol) would not be stiff and a shot of whiskey would be stiff; as a comparison.
strong or potent to the taste or system, as a beverage ormedicine: He was cold and wanted a good stiff drink.
The cast of A Stiff Drink - 1996 includes: Ruth Gemmell as Woman Cal Macaninch as Man
Soda?
stiff
To get a Stiff, or Stiffy, is school playground giggles for an erection
To jump with stiff legs means to lock your knees.
Stiff
When a chronic alcho has a stiff drink he will stop "shaken"
Short,stiff hair
stiff or made out of wood
Short,stiff hair
drawing Circles