lohanapp042613.jpg

She's the queen of pet projects!

Lindsay Lohan is lending her star power to her brother Michael's new karaoke app, and the rehabbed redhead stands to make a pretty penny if it turns out to be a success!

The app, called Just Sing It, was developed by Michael and co-founder Alec Andronikov and is marketed as "like Instagram for your voice." Lilo has been using Twitter as a way to recruit more users, often challenging them to play against her. She even tweeted a pic of herself playing recently with the caption," Who's up for a @justsingit challenge?!"

"People must be asking, 'Why is she playing [the app], why is she endorsing this product?' She knows I am an owner and was a lot more willing to participate in a heartfelt way," Michael told the New York Post.

Apparently, the app has been downloaded 100,000 times since it launched less than a month ago and a million songs have been shared on it!

The younger Lohan might want to line up a new spokesperson because his famous sister is headed off to rehab soon!