This phrase was apparently popular in some circles in the early 1990's... according to this philosophy professor I had this one time.
Advantages of the phrase 'lightly toasted' over other more common terms:
1 - It is basically a thinly veiled version of the more popular adjective 'baked,' and yet it is somehow ambiguous enough to be used in virtually any environment without anyone being the wiser.
2 - It invokes images of lightly toasted food, which is always pleasurable to think about and even better - to consume when you yourself are 'lightly toasted.'
3 - You can insert the phrase into a sentence about food and in so doing tip off only those cool enough to understand.
(the stealthy approach):
"Hey guys, I could go for some *lightly toasted* Popped Tarts right now... (wink wink) What about you guys?"
(or it can even serve as sexual innuendo):
"Hey baby, let's get lightly toasted then you can butter my bacon while I scramble your eggs."
The possibilities are endless. So, go out there and spread the good word my friends. We won't stop until the whole world is golden brown.