A vagrant slashed another man who confronted him for masturbating in front of his wife outside Penn Station late Wednesday, according to cops and police sources. 

The unidentified 21-year-old suspect – who is listed as a “John Doe” in police records – was pleasuring himself near the married couple at the corner of West 34th Street and Seventh Avenue around 11:20 p.m., according to cops and police sources. 

The husband, 31, told the homeless man to cut it out – prompting him to slash the man in the hand with a razor, authorities and the sources said. 

The victim refused medical attention for a minor cut on his hand, cops said. 

The suspect fled into Penn Station, where cops found him and took him into custody, police said. 

He was charged with public lewdness and assault, authorities said.