grill mumble

(verb) Inarticulate manner of speeking brought about by the presence of metal dental retainer or grill in one's mouth
(noun) word or phrase charcterized by being spoken through one's grill
(noun) condition of being rendered incoherent by the presence of a grill

The artist replied, hampered by his grill mumble, "You said I'm left off 'Bad and Boujee?"