Iman Shumpert -- I'M NOT GUMBY DAMMIT ... Ditches Signature Hairdo

It's the end of an era in the NBA ... 'cause Cavs star Iman Shumpert just ditched his signature Gumby-style high top cut ... for a brand new dreaded up man bun.

Shumpert was out in L.A. with his pop star girlfriend Teyana Taylor when we noticed that he didn't bring something with him on his trip to the coast ... his one-of-a-kind hair.

Check out the clip -- Iman ... who's just signed a $40 million dollar deal with Cleveland ... says he just wanted a change and that Teyana supports his new 'do 100%.