A more intense version of "foig." Foig tends to be a Vancouver word, much like the word "ceeb." The origins of both words cannot be certain though in terms of which school started using them first. In this case though, VC started troig along with its many extensions. Troig means tripple foig, hence a more intense version of foig.
Jack "Yo that big foig is walking towards us, lets all call him a troig when he walks by... TROIG!"
Andrew "hahaha what a Lloyd!"