Matt Barnes -- The NBA Is the Grinch That Stole My Kids' Christmas! (VIDEO)

Matt Barnes' kids are getting socks and underwear for Christmas this year ... and the Los Angeles Clippers baller says they can blame the NBA for it.

Barnes was still fuming Sunday night over his fine from the league this week ... $25,000 for kicking a water bottle (the league says it's also for cursing at a fan).

The swingman explained why he thinks the league came down so hard on him -- and told us how he was planning to spend that dough.