Uh oh.
Dikembe Mutombo says reports that he personally gave Bismack Biyombo his blessing to use the signature finger wag is COMPLETELY FALSE ... telling TMZ Sports, "Him and I need to talk."
Biyombo has used the finger wag a couple times during the NBA playoffs -- most recently busting it out Monday night after a block during the Raptors victory over the Cleveland Cavs.
Mutombo says he's seen reports that he had a conversation with Bismack in which he formally bestowed his finger-wagging blessing ... but insists the reports are simply not true.