Article continues below advertisementKathy Griffin witnessed Justin Timberlake acting rude toward then-girlfriend Britney Spears years ago.In a clip from her latest YouTube segment, the comedian recalled working with the former couple for a bit at an awards show and revealed the *NSYNC alum didn't give off great vibes.Article continues below advertisementKathy Griffin Shades Justin TimberlakeSource: @kathygriffin/instagramKathy Griffin witnessed Justin Timberlake being 'not respectful' toward Britney Spears when the pop stars dated.