Dirty What?!?!?

For the last year i have been curious to what in fact was a "dirty sanchez". I heard it in a tangent of foul sounding sexual acts in a speech in Forty Year Old Virgin (rent it, buy it, love it) and again tonight in the audio commentary of Fun with Dick and Jane (written and produced by a Freaks & Geeks alumn Judd Apatow).
The hubby googled it and the answer was disturbingly loathsome. More retched then snowballing (heard and defined in Clerks).