Lourdes Leon Goofs Off In Mom's Famous Cone Bra

Lourdes Leon is growing up ... fast!

The 15-year-old daughter of Madonna put on mom's cone bra backstage while sticking out her tongue ... and um, holding on tight to the cones. Along with this provocative photo posted on the Material Girl clothing line Twitter account was the following: "Lola backstage at MDNA!"

This cony creation was first worn by Madge back in 1990 during her controversial Blond Ambition tour.

Let's hope lil' Lourdes doesn't go any further with mom's old habits!