Matthew Koma revealed that he and wife Hilary Duff dressed up as the Madden brothers for Halloween.

Cindy Ord / Getty Images for Vanity Fair, David Livingston / WireImage

On his Instagram story, Matthew shared a picture of him dressed as Good Charlotte singer and Inkmaster host Joel Madden.

Matthew Koma / Via instagram.com

And then a picture of Hilary as Benjamin. The occasion? Dinner with Joel and his wife Nicole Richie!

Matthew Koma / Via instagram.com

Joel, Nicole, and Hilary all seemed to be fans of the move, sharing photos from the moment on their Instagrams.

Hilary Duff / Via Instagram: @hilaryduff

What makes the move slightly odd and/or noteworthy is that Hilary used to date Joel from 2004-06. Mathematical minds will remember that this began when Joel was 25 and Hilary was 16.

Lawrence Lucier / FilmMagic

However, the families have remained close, as Hilary said last year, "We’re neighbors and we actually hang out all the time. I was just in [Nicole's] driveway honking for her to come drink wine with us the other day."

Christopher Polk / FilmMagic

So, er, what do you make of this?