devil-may-care

carefree, casual, lackadaisical, nonchalant, unaffected, unconcerned, unfussy, unperturbed, untroubled, unworried

familiar, homey (also homy), informal

flexible, lax, lenient, permissive, pliable, pliant, soft

accessible, approachable

imperturbable, nerveless, unflappable, unshakable

amicable, companionable, comradely, cordial, genial, hail-fellow-well-met, hearty, neighborly, warm, warmhearted

adventurous, audacious, bold, daring, venturesome

hasty, headlong, hotheaded, impetuous, precipitate, rash, wild

blithe, carefree, happy-go-lucky, madcap, slaphappy

nonchalant, unconcerned, unworried

careless, freewheeling, heedless, inattentive, incautious, mindless, regardless, unheeding, unmindful

feckless, inconsiderate, thoughtless, unthinking

blasé (also blase), breezy, cavalier, nonchalant

casual, easygoing, informal, laid-back, low-pressure, relaxed, unfussy