Justin Timberlake embarrassed his mother by kissing girlfriend Jessica Bielin front of her after Sunday's MTV Video Music Awards.The 'SexyBack' singer celebrated being named Best Male Artist at the ceremony by going for dinner at Tableau restaurant in the Wynn Las Vegas Hotel's Spa Tower with Biel and his mom Lynn.Eye witnesses claim Justin, 26, couldn't keep his hands off Jessica, despite the presence of his embarrassed parent.A fellow diner told People magazine: "They were kissing and being so lovey-dovey. They were always touching and being very sweet with one another and all in front of Justin's mom."Justin is believed to have gone straight home after the meal because he was feeling unwell.The singer was reportedly ordered by a doctor to rest his voice yesterday after suffering "vocal strain" caused by his impressive closing performance with Timbaland and Nelly Furtado at the star-studded ceremony and months of touring.He has had to cancel planned performances in Sacramento and San Jose as a result.