Heidi Klum is clearly really comfortable with her colleagues.

The 5-foot-9 model and fellow Project Runway judge Zac Posen had a little fun together in a photo posted on Instagram on Thursday.

In the photo, Klum appears in nothing but an underwear and the fashion designer uses his hand to cover her chest.

"@zac_posen ....I need something to wear for tonight's @projectrunway @lifetimetv," Klum wrote as the caption.

However, the star is no stranger to posing nude. For example, Klum appeared in a spread for Allure magazine in 2012 completely naked and used her hands to cover her private parts.

This year, Klum also went nude for a new photo shoot that supports AIDS research. The only thing covering the 41-year-old in the photos taken for The Foundation of AIDS Research was a tote bag.

"Our longtime friend @HeidiKlum bears all for @amfAR to help us launch the release of a special edition canvas tote bag designed by the renowned @JPGaultierOfficial to raise HIV/AIDS awareness," the foundation wrote as the caption in May.

"Make a statement this summer and support #AIDS research like @heidiklum with the #amfARTote by @jpgaultierofficial. Now available in-stores and online @scoopnyc. Proceeds from every bag purchased benefits amfAR’s research programs," they later wrote in another photo posted in June.

Tags: Heidi Klum