A 28-year-old Dorchester man ?accused of exposing himself while urinating into a women’s room sink at an MBTA station allegedly told a woman who caught him in the act: “This is a men’s bathroom now!”

Taha Hamid was arrested about 10:30 a.m. Friday after a woman told a transit cop the Dorchester man had just entered the women’s room at the MBTA’s Back Bay Station, “pulled down his pants fully exposing his genitals to the victim … then proceeded to urinate into the sink,” according to police.

The woman said that as Hamid was relieving himself into the sink, he shouted: “This is a men’s bathroom now!”

Hamid was arrested on a charge of open and gross lewdness. He is expected to be arraigned in Boston Municipal Court.