To adorn unnecessarily something already beautiful. The expression is a condensation of Shakespeare's metaphor in King John: "To gild refined gold, to paint the lily ... is wasteful and ridiculous excess." i.e., you wouldn't need to add gold to a beautiful lily.
The act of shoving a largedildo up a young Jewish girl's ass, pulling it out, licking it and then shoving it into her pussy. Not to be confused with the very popular "golden sponge bath."
Ari and Levana were having nice, clean sex when Ari grabbed Levana's dildo and began Gilding the Menorah.