The legend of this international holiday goes something like this. One day (June 6, 1995, to be exact) a pair of "guys" as they refer to themselves ~ Mark and John ~ lapsed into pirate slang while playing racquetball on Court #3 at the Albany, Oregon YMCA. They had so much fun with this that immediately following the match, they decided that what the world really needed was a new holiday, i.e. "Talk Like a Pirate Day" (TLAPD).
Why September 19 and not June 6? From the Official Talk Like A Pirate Day website, "As any guy can tell you, June 6 is the anniversary of World War II's D-Day. Guys hold dates like that in reverence and awe so there was no way we could use June 6.
"Mark came up with September 19. That was and is his ex-wife's birthday, and the only date he could readily recall that wasn't taken up with something like Christmas or the Super Bowl or something."