|Cadbury's Laughs Bar - TV Comic, 6 October 1973|
Yes once upon a time in 1973 that was the case and a Cadbury's bar to boot.
Except despite the fact my Grandfather owned a shop and I probably had a reasonable amount of exposure to chocolate by the time I was 5 (when this ad appeared) I don't really remember Cadbury's Laughs bar.
According to this advert each wrapper contained one of 6 tricks such as "the mind-where-you-sit trick" and "the umbrella trick".
I was probably too busy collecting Nestle Robin Hood wrappers at the time...