hotheaded
impulsive
impetuous
madcap
tearaway
brainish
characterized by undue haste and lack of thought or deliberation
a hotheaded decision
liable to such impulsive acts as hugging strangers
an impetuous display of spending and gambling
madcap escapade
daredevil
hothead
swashbuckler
lunatic
harum-scarum
a reckless impetuous irresponsible person