SurveyUSA estimates that at least 18 million Americans have now been “Rickrolled,” according to this latest national poll of 959 adults, conducted 04/08/08.

Understanding and explaining the phenomena can be difficult, although this article is helpful. Essentially, the most common usage is as follows:

Pranksters post links on various internet sites, in instant messages to friends, or in email that purport to direct to something of interest, but which instead link to a YouTube video of the 1987 hit by British singer Rick Astley. Originally a purely underground happening, Rickrolling has recently made significant inroads to the mainstream, possibly culminating with yesterday’s performance of the song during the 8th inning of the New York Mets home opener Tuesday afternoon.

Baseball fans may not have cared for the song, but we thought we’d take a look, for the record, at what may end up being the very peak of the fad, and find out how many people say they’ve been Rickrolled. Nationally, the number is 6% — and multiplied out by 300 million Americans, that means at least 18 million Americans have been on the receiving end of the prank. Note that this is likely an underestimation, as the poll was unable to include those under the age of 18. Full results are here.