Ashlee Simpson threw a White-Trash themed party in celebration of her 24th birthday last weekend.

Celebrity pals Nicole Richie, Joel Madden, and Christina Aguilera were on-hand to help the heavily-pregnant star celebrate her big day.

“It had a white-trash theme. Ashlee wore Daisy Duke hot-pants and platform flip-flops with a bathing suit and a fake tattoo around her belly,” one guest said in a scoop to PEOPLE Magazine on Wednesday.

Even big sister Jessica and her papa Joe got into the spirit by dressing up in “trashy” outfits.

“Joe wore a cut-off muscle T-shirt and a mullet wig. It was funny. Jessica was wearing a crazy leopard-print dress that showed off a lot of cleavage.”