Letterman's rhymes with:
bitterman's, bittermann's, waterman's, bitterman's, bittermann's, fisherman's, leiderman's, lieberman's, liederman's, schneiderman's, wasserman's, waterman's, zuckerman's
Letterman's sounds like:
latrines, leiderman's, lettering, liederman's, littering, loitering, lutherans