play good cop / bad cop on the site.
Let about 3 seconds of it go- then cut the video/music- pop up a very boy-scout looking box on top of the screen (so anyone looking at the screen wouldn't see any dick) with "your PC registry contains spyware that is playing lewd material - XYZ program can remove this now if you click here, if you do not be forwarned this malicious software will take over your browser with gay porn (well-worded).
If they click "no thanks" go back to dickroll - on the next mouse click pop the same box.
I bet your conversions for that shit would be nuts - if you wanna get real slick figure out a way to pause/hide the dickroll while the purchase goes through and pixel fires, if they don't purchase continue to dickroll.