The pregnant 38-year-old singer looked unrecognizable as she transformed into Danny DeVito's character, Vincent Benedict, from the 1988 comedy Twins, while her husband dressed up as Arnold Schwarzenegger's Julius.
For their creative costumes, they both wore matching white suits with blue-and-white printed shirts, tan shoes and shades. The expectant mother also shared a Boomerang of herself and her husband walking and throwing their blazers over their shoulders.
"TWINS #DannyDeVito #ArnoldSchwarzenegger #HappyHalloween," Simpson captioned her Instagram pics. The awesome costumes also caught the attention of the singer turned designer's parents, who couldn’t help but praise their daughter for her unbelievable transformation.
"Jess, you win best costume!! I had no idea who you were. Danny would be proud," Joe Simpson wrote.
Tina Simpson also commented: "SERIOUSLY as a MOM I have never laughed so hard when I walked into her Halloween party and saw this! BEYOND! And I will post a video of her walking which is beyond…@dannydevito you have to watch a glam girl channel you! HAHAHAHAHAHAHHAHAHAHAHA my tummy is aching from tonight. I love you my baby @jessicasimpson."
There was definitely a slew of great celebrity couples costumes this year. Bella Hadid and The Weeknd dressed up as Beetlejuice and Lydia Deetz, Dylan Sprouse and Barbara Palvin were Dragon Ball Z characters and Gwyneth Paltrow and Brad Falchuk became Jack and Ally from Bradley Cooper and Lady Gaga's 2018 remake of A Star Is Born.