I am no Hustler magazine reader and in the seventies i would have been to young anyways, so i have not seen that advert.
There is a handfull of LED watches that had a built-in message, often "Lets F*ck" "Time to F*ck". Hughes Aircraft was afaik the only manufacturer to ever make a programmable module so the user could set his own text.
I have one of the legendary "Lets F*ck" hard-coded message watches as well as a good condition programmable one. If you're interested in trading then please drop me a message.