A term playing off of
MILF (Mother I'd Like to Fuck) except the G stands for one of many things: Grandmother, Grandfather,
Girl, or
Guy. As such it can be used as a gender neutral term.
"Damn that
dude is such a GILF, I'd pay money for a piece of that change"
OR
"Holy shit that old
lady must bathe in the fountain of youth,
totally a GILF"