Ruby

buhii = Enumerator.new { |y| loop { y << 'ブヒィ'.split('').sample } }
buhii.take(50).join
# "ヒィブブィィヒィブブブィブヒィヒィィヒィヒヒヒヒブブブィブヒヒヒブィィヒブヒィィヒブヒヒヒブヒィブブ"

system("say #{buhii.take(50).join}")

Python

import itertools
import random

def buhii():
  while True:
    yield random.choice([chr for chr in 'ブヒィ'])

''.join(itertools.islice(buhii(), 50))
# 'ィブブヒヒヒヒィブブブヒィィィィブブヒヒブブヒヒィィヒィィィブブィィブィィヒヒヒィヒヒブィィヒヒヒィ'

JavaScript

const sample = (array) => array[Math.floor(Math.random() * array.length)];
const times = (n, fn) => (new Array(n)).fill(null).map(fn);

const buhii = function* () { while (true) yield sample('ブヒィ'.split('')) };
times(50, () => buhii().next().value).join('');
// 'ヒブブヒィィィィヒィヒヒブブィィブィィィヒブヒヒブヒヒヒブィブブヒヒヒヒブヒィヒヒヒヒブィヒヒィィィ'