We all know that thumbs up means 'right'? Good luck! Well done! Spiffing! etc etc. Well, when I was a kid growing up in Footscray, that gesture had a rather different meaning to us.
One day in 1963 or thereabouts I and a few of my closest friends were taught, in the coarsest possible terms, by someone maybe 2 years older than we were, about the mysteries of sex. I say coarse advisedly; not a lot of subtlety was employed.
This was way before I reached puberty. So I'm at a loss, in these later years of maturity, to explain why it was that I was siezed with an insatiable desire to perform the act. But siezed I surely was!
We were taught, in the course of that lesson, that the signal to a girl that one was interested was a thumbs up! This was somewhat before this[^].
So we spent interminable hours after school thumbs upping at anyone who bore the slightest femininity. Maybe some coarse language was also involved; I'm pleading the fifth! :-) But I should admit that I was one of the worst offenders. Oh, and we had one other incredibly subtle approach if the thumb failed, as it invariably did; approach and ask 'are you a girl?'. If the answer was in the affirmative - 'Prove it!'. Yeah, that had a lot of prospect of success! Smacks on the ear were the most usual response!
Eventually we were hauled up in front of the headmaster. A little beating about the bush. The head wanted to know what we meant when we did the thumbs up. We, of course, dissembled. Innocent looks; we didn't know what it meant. Suddenly he rounded upon us. 'When you disgusting little boys do that' (thumb thrust up in the air) 'you mean 'want to f????'. It was true; that was indeed what we meant. But I can't describe to you the shock of hearing that word coming from our august head's lips. Getting six of the best upon my upturned palm was almost an anti-climax after that!