Engaging in coitus, the physical act of love-making, with a now old and decrepit former bombshell for the pure reason of going where so many once desired.
Grace Slick of the Jefferson Airplane was a smoking fox back in the 1960s and 1970s. Now, she is hardly a silver fox. But you would still bang her because you can brag about fucking Grace Slick; a legacy fuck. Of course, when you do tell everyone about having sex with Grace Slick, you would refrain from revealing when and how much K-Y jelly you went through to slick up the Slick. That does not matter. What does, is that you came inside a sex symbol. Hey, they (Elizabeth Taylor, Tara Reid, Anne Bancroft, Monroe, Janice Dickinson, etc.) still look great on Google Images, which is the medium through which most see said "legacy fuck."