Article continues below advertisementSydney Sweeney turned up the heat in a risqué video promoting her new lingerie brand, Syrn.The actress, 28, bared her lean physique in white underwear and a matching tank top while kneeling seductively on the ground in a Thursday, February 26, upload.The clip then cut to a topless Sweeney straddling a black chair, wearing nothing but a thong and sheer tights.Article continues below advertisementSource: @sydney_sweeney/InstagramSydney Sweeney starred in a racy new fashion campaign.