Green’s Dictionary of Slang

1. (US) a fool.

1960

G. Swarthout Where the Boys Are 10: I want serious readers, not a bunch of BB-stackers.

2. (US teen) a female with large breasts (stereotyped as stupid).

1961

F. Kohner Gidget Goes Hawaiian 22: ‘Boy – she’s my type,’ said Wally. ‘A real B.B stacker.’ That irked me. It was so typical. Those surfing jocks just refuse to give me female status. When they see a talent like Abby their glands go berserk. It never occurs to them that I am a woman, charged with the same emotions and desires that would put a Monroe to shame. I’m just the Gidget.