The star of TV show Chuck appears in Three Pop Stars, One Song, wearing prosthetic Katy Perry-style cream cake breasts, Gaga shoes and sunnies and as a Jack Daniels-swigging Ke$ha who is sick in a toilet.
As Katy, she sings: 'I put on makeup, a lot of makeup, and you fell in love with my ass.'
'I'm from the year 3000, I'm here to eat your penis' is one of her Gaga lines.
As Ke$ha, she sings, 'I just woke up in your toilet, I'm covered in Jack and vomit' and 'I love you more than herpes.'
At the end of the video she appears as a hoodie-wearing Justin Beiber singing, 'I will be your girl' who then says, 'Actually, I'm a guy.'
Yvonne, 28, filmed the clip for the website collegehumor.com and it has now been posted onto YouTube.
She will soon appear in the new Melbourne-shot movie The Killer Elite with Robert De Niro, Clive Owen and Jason Statham.