Green’s Dictionary of Slang

(US campus) to eat voraciously.

1983		T. Paulin ‘Off the Back of a Lorry’ in Liberty Tree 31: Two rednecks troughing / in a gleamy diner.
1996		Eble Sl. and Sociability 31: Sometimes the word + particle construction is typical of and strengthens the synonymy of a group of related verbs: [...] pork out, snort out, throw down, and trough out all mean ‘to eat, usually quickly or in great quantity.’.
2000		Guardian Rev. 17 June 12: I would then resume troughing madly.