Calvin Klein's ex busted for punching man after night of partying

Lawrence Schwartzwald/Splashnews

Calvin Klein with Nicholas "Nick" Gruber.

Calvin Klein’s former boy-toy was arrested this morning for allegedly punching a man he took home after a night of partying, sources told the Post.

Model and former paramour of the fashion great, Nicholas Gruber, 22, allegedly clocked a man he brought to his Greenwich Street penthouse after a get-together, sources said. The 20-year-old victim, who lives in Manhattan, told police he suffered a cut to the face in the 4:20 a.m. fight.

When cops arrived, Gruber flailed his arms in an attempt to avoid being cuffed and shoved his hand into his pants trying to conceal something, sources said.

The boy-toy was strip-searched at the 6th Precinct station house, where police reportedly found cocaine in his underwear.

Gruber – who grabbed the spotlight when he began parties in the Hamptons and Manhattan with his much older fashion-designer boyfriend, was charged with misdemeanor assault, resisting arrest and possession of a controlled substance.

kconley@nypost.com