David Schwimmer Justin Bieber matching hair

David Schwimmer and Justin Bieber sport matching 'dos. Photos: AP | Getty Images

Oh, this isn't good.

Just when designer Thakoon Panchigul told Menswear magazine that the Justin Bieber 'do is a definite "don't," here comes David Schwimmer wearing the shameful shag.

The 43-year-old actor -- 43!!! -- was seen sporting the 16-year-old's signature coif at a Shakespeare in the Park production of "The Merchant of Venice" at NYC's Delacorte Theater.

43!!!

Sorry. But if 32-year-old New England Patriot/model Tom Brady couldn't pull off Bieber bangs -- and trust us, he couldn't ("I think the Justin Bieber look is a little too young for him," Sandy Poirier of South Boston's Shag Salon told the Boston Herald of Brady) -- no man approaching middle age should even consider it an option.

Forty-three-year-old Schwimmer (sorry, that number bears repeating) resisted getting The Rachel during his "Friends" days, so it seems strange that he's suddenly started chasing hair trends now.

If he must copy a current coif, we'd much rather he stick to the shorter Moe -- which has seen been seen in recent months on everyone from Lady Gaga to Rihanna -- and leave the Bieber look to the kids.

In related sad men's style news, read about the Speedo making a comeback.