As an adult, I have heard people affecting a stammer or a stutter.
Lyle said that Harold, whose last name he believed was Smith, had a stutter, and rode a beach cruiser.
But Rachel Fine, whose father, brother, nephew, and son all stutter, best summed up the benefits the organization.
1560s, frequentative form of stutt, from Middle English stutten "to stutter, stammer" (late 14c.), cognate with Middle Low German stoten "to knock, strike against, collide," from Proto-Germanic *staut- "push, thrust" (cf. Old English stotan, Old High German stozan, Gothic stautan "to push, thrust"), from PIE *(s)teu- (see steep (adj.)). The noun is attested from 1854.
stutter stut·ter (stŭt'ər)
A phonatory or articulatory disorder characterized by difficult enunciation of words with frequent halting and repetition of the initial consonant or syllable. v. stut·tered, stut·ter·ing, stut·ters
To utter with spasmodic repetition or prolongation of sounds.