The NBA has fined Isaiah Thomas $25,000 for "directing inappropriate language toward a fan," stemming from an incident during Game 3 at the Verizon Center in D.C. 

During Boston's loss, Thomas briefly got into it with a heckling fan and the interaction was caught on tape from someone else in the crowd.

Although you can't hear exactly what the fan is saying to Thomas, you can clearly see the 5'9 point guard call out to the fan and say, "I will fuck you up. And you know that. Just make sure after, you come right here and say it."

Thomas won't have any such issues with unruly fans tonight as the series shifts back to Boston for a pivotal Game 5.

Check out the clip below.

"I will f--k you up and you know that" (Submitted by @thesportytraveler)

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