"Hey! This thing talks!"
OK, so we've proved that making your Speak and Spell machine swear is neither big nor clever, and frankly, what's the point of spelling out the swearage if the damned thing refuses to say the words? Moving on from this travesty of antique electronic engineering, which could only be made to swear in the most roundabout way, it pleased me somewhat that my paper-round money allowed me to go out and buy a basic speech synthesiser for my BBC Micro - the spiffy "Speech!" by Superior Software.
A triumph of the programmer's art, you could actually get the machine to say real, life stuff without the need for any expensive extra chips. Load up the programme (which hid itself in the upper reaches of the Beeb's massive 32kB memory, and by typing *SAY "Fuck off", your Model B became a top quality cussin' machine. Oh, japes.
As luck would have it, our college had just taken delivery of a job lot of BBC Micros for their computer lab, consigning their old PETs with the built-in green screens to the dustbin of history (next to the kitchen slops bin out the back). Being a l33t BBC Model B programmer, it was time to wreak Juvenile Geek Computer Havoc!
It was only a matter of time before traps were left for the next user. Confronted by a blank screen containing only the words "Hit any key", they would do as requested, and the profanity would last right up to the moment they switched the thing off.
Nowadays, the same effect can be created by goosing up Professor Stephen Hawking's daughter.