Green’s Dictionary of Slang

not the full... phr.

In phrases

...cup of tea (also not the full bottle) [synon. for not all there adj.]

not very intelligent, slightly eccentric, odd.

1986
19901995
1998
Show quotations
[Aus]R. Beckett Dinkum Aussie Dict. 38: Not the full bottle: Means that someone is ‘not the full quid’.
[UK]G. Burn Happy Like Murderers 93: She wasn’t the full cup of tea in her brother Andrew’s opinion.
...the full deener

(Aus.) not very intelligent.

1962
Show quotations
J. McNeill How Does Your Garden Grow? in Dutton Lit. of Aus. (1976) 288: sam They do say, sir, that I’m...ahh, well, they do say that I’m not the full deener.
...dollar (also only ninety-nine cents out of the dollar)

(US/Aus.) not very intelligent, slightly eccentric, odd.

1863
190019502000
2002
Show quotations
[UK]G.A. Sala Breakfast in Bed 80: ‘Uncle Abe’ had only ninety-nine cents out of the mental dollar.
Wattle Creek Wire No. 16 Fall, at Wattlecreek.com 🌐 People for years have correctly questioned my sanity and when you consider the time line in establishing a winery, you will probably agree with the masses that I am not the full dollar.