flaunted her bikini bod in a black polka dot bikini over the weekend while on vacation in Cabo San Lucas with a few of her friends. Pairing the two-piece with a straw hat and shades, Ashlee took a dip in the pool and was later joined by her new boyfriend, Boardwalk Empire
star Vincent Piazza
Later in the afternoon, Ashlee and her sister Jessica Simpson were photographed treating birthday girl, Nicole Richie, to lunch.
Richie, who just this past Wednesday celebrated turning 30 years old, apparently had more in store than just her party in Los Angeles that was a star-studded affair. Nicole kept the party going by jetting off to Mexico, where she was spotted soaking up the sun in a black bikini with pal Samantha Ronson