Triple tautonyms are hard to find. I know if only two in Webster's Third Edition, cha-cha-cha and tat-tat-tat. On page 175 in his book Language on Vacation (Scribner's, 1965), Dmitri Borgmann also suggests the college sororities Delta Delta Delta and Sigma Sigma Sigma, the honor society Beta Beta Beta, and the scientific names for the African weaverbird and the common rat, Quela quela quela and Rattus rattus rattus (misspelled with a single T). There are a few legitimate additions to his list, such as the movie title Tora! Tora! Tora!; much less acceptable are juxtapositions of the Row, Row, Row your boat ... variety.
Wolpow, Edward R.
"Triple Tautonyms in Biology,"
Word Ways: Vol. 16
, Article 10.
Available at: http://digitalcommons.butler.edu/wordways/vol16/iss2/10