US First Lady Michelle Obama is to make an appearance on hit television comedy iCarly, to help promote one of her pet causes, according to the Nickelodeon TV network. Barack Obama\'s wife will play a cameo role to promote Joining Forces, which aims to boost support for military families, in an episode expected to be aired in January. \"She\'s guest starring... she\'s going to be talking about her Joining Forces initiative,\" Nickelodeon spokeswoman Adriana Lemus told AFP on Wednesday. Obama appears \"in the most positive way possible\" as part of a web chat between the show\'s main character, Carly Shay, and her father serving overseas in the military, according to reports confirmed by Lemus. The First Lady is expected to visit California next week for fundraising events, according to local media reports. The Nickelodeon spokeswoman declined to say whether she might record her iCarly spot during that trip.