Kobe Bryant is pissed at Dwight Howard ... so much so he did the worst possible thing you can do to a person ... he UNFOLLOWED HIM ON TWITTER.

Pause for reaction.

That's right, just after Howard announced he was ditching the L.A. Lakers for greener pastures ... i.e. the Houston Rockets ... Kobe made sure to axe D12 from his Twitter feed.

Fellow Laker Pau Gasol also unfollowed Howard -- but reportedly changed his mind 20 mins later.

Which is kind of more pathetic, yeah?