harum-scarum

nouns

a reckless impetuous irresponsible person
daredevil, harum-scarum, hothead, lunatic, madcap, swashbuckler

adjectives

cheerfully irresponsible
"carefree with his money"; "freewheeling urban youths"; "had a harum-scarum youth"
carefree, devil-may-care, freewheeling, happy-go-lucky, harum-scarum, slaphappy

adverbs

in a wild or reckless manner
"dashing harum-scarum all over the place"; "running pell-mell up the stairs"
harum-scarum, pell-mell