So the Times Sunday Style section published a Stephanie Rosenbloom piece on the word "vajayjay." Maybe a few thousand older readers of the paper simultaneously recoiled in terror... but that's the price of trend journalism in the '00s. Rosenbloom wrote that "vajayjay" originated was first popularized on Grey's Anatomy.

But there's no research staff out there like the dedicated infojunkies of the internet. This comment on Fimoculous posits an earlier origin for "vajayjay":

I'm sure this term has been even longer. The first time I heard it was in an MC Paul Barman song "MTV get off the air pt.2" from his 2000 EP It's Very Stimulating, in which he trades retardedly brilliant sex rhymes with Princess Superstar.

Among other gems, this appears towards the end of the song:
"Lady, one more complaint
and I'll shove a rape-whistle up the Mrs. Va-J-J"