devil-may-care

Adjective

• marked by a carefree unconventionality or disreputableness
  • a cocktail party given by some...raffish bachelors- Crary Moore
    

• cheerfully irresponsible
  • carefree with his money
    
  • freewheeling urban youths
    
  • had a harum-scarum youth
    

Related words

• Synonyms: 
  raffish , rakish , carefree , freewheeling , happy-go-lucky , harum-scarum , slaphappy