NBA Star JaVale McGee -- I've Got a RIDDLE for You!!!!

The only thing Denver Nuggets star JaVale McGee likes more than a goofy outfit ... IS A GREAT RIDDLE ... and last night, he challenged TMZ to a quality brainteaser right on the street!

Here's the deal ... McGee was leaving Crustacean in L.A. last night when one of our photogs hit up the 7-footer with a bunch of random, weird questions ... like, "How much would your $44 million contract weigh in gold bars?"

McGee didn't like the fact he didn't know the answer ... so he totally turned the tables -- and asked a riddle of his own!

The whole exchange is pretty funny ... our photog's a goofball, JaVale's a goofball -- turned out to be a pretty hilarious encounter.