If you don’t mind going just over the border into Maryland, Take the red line to Silver Spring, walk a few steps to the bus depot, and catch the #20 bus that leaves on the second floor [Edit for clarity]. Turn left at the top of escalator, and the stop for #20 is right there. Ride the #20 about 15 minutes to New Hampshire and Elton Sts, and walk across the parking lot to 10141 New Hampshire Ave where there are two very large thrift stores next to each other: Unique and Value Village. There are many aisles of men’s clothing in both those stores.