Is this something like a pre-flash that is used by some for speed boost?
Almost. Pre-flash for speed enhancement (or for contrast control in printing) is kept low enough not to produce density above base+fog on its own; it's typically about one stop below Zone 1 exposure.
@Bill Burk is proposing deliberately fogging well above that level. To simulate, say, forty years of age fog, you'd probably want to pre-expose at around Zone II level; you'd then need to expose your image about two to three stops below your usual film speed to lift it out of the base + (intentional) fog. I'd go against his suggestion, in part; I'd go ahead and develop to higher than normal contrast; this in itself tends to accentuate grain. The resulting negative may be a little challenging to print well (as would be the case with decades-old film), but ought to give all the grain you're going to get from a given film.
Combine this with starting with a known grainy film (Fomapan 400, for instance, or as suggested above Delta 3200 or T-Max P3200) and you're well on the road for a "sixty grit" look.