Hmm..

It could be that:
Rafiki is annoying Simba to get his attention
Simba tells him to cut it out
But Rafiki needs Simba's attention so he continues
He can't 'cut out' being annoying because he needs to speak to Simba, and if he did cut it out, he still needs to speak to Simba, so he would annoy him again, effectivly his annoyance 'growing back'
Sorry if that makes little sense, it's incredibly difficult to explain what i'm thinking
