Green’s Dictionary of Slang

general term of praise, admiration; serious, important, excellent; thus crucially adv.

1987		Eble Campus Sl. Oct. 2: crucial – good, positive.
1994		M. Montague Dread Culture 85: It belong to dis Rastaman who teach us all sort a tings. Di man crushal.
1999		(con. 1979–80) A. Wheatle Brixton Rock (2004) 21: This is Brenton – the guy who crucially dealt with Terry Flynn.
2001		Source Aug. 47: Being willing to ‘ride or die’ for whomever you’re protecting is ‘crucial’.
2012		K. Powers Yellow Birds 61: I remembered a cav scout in Al Tafar writing down the address for me [...] ‘Best fucking place in history to get your dick wet. Fucking crucial’.