Green’s Dictionary of Slang

(US) to make a loud derisive noise, as if breaking wind.

1932		Lubbock Morn. Avalanche (TX) 11 Nov. 8/5: A down-front dozen of high school students hooted and Bronx cheered joyfully.
1933		Shamokin News-Dispatch (PA) 29 Nov. 4/1: Police Judge Taggart [...] fined the man $15. Ryals tossed bnack his head and issued a robust Bronx cheer. Angered, the judge added 10 days in jail. Again Ryals gave the salute. The judge increased the sentence to 30 days. Ryals Bronx cheered again.
1934		E. Dahlberg Those Who Perish 104: Two loafers standing at the edge of the curb bronx-cheered and yelled: ‘Melamed, Melamed — hey, rabbizin!’.
1940		B. Appel People Talk (1972) 45: A drunk bronx-cheers everybody, salesmen and spectators.
1990		S. Morgan Homeboy 314: The opening bars of ‘Fascination’ were Bronx cheered through a saxophone.