Jessica Simpson was overheard telling her mother Tina during a recent New York awards show (the Accessories Council ACE awards at Cipriani 42nd Street) that her younger sister is stupid.
"Mum, Ashlee is so stupid. She left the popcorn in the microwave and almost burned the house down", Jessica said.

The 'Dukes Of Hazzard' star has also expressed her concern about Ashlee's party lifestyle, especially now, that she is 21. Apparently, the "Pieces of Me" singer was video taped swearing at a McDonald's employee while she was drunk, in Canada.

Last month, Ashlee was spotted making out with two young men on the same night, while celebrating the launch of her new album 'I Am Me' at exclusive New York bar the PM Lounge.

Jessica Simpson is worried that her sister is going out too much and suggests her to slow down for the sake of her career.

Meanwhile, Jessica is reportedly fighting for her marriage with Nick Lachey, which is apparently on the rocks.