Impulsive Behavior

adjective showing a lack of good sense or judgment; foolish

• His foolheaded decision to invest all his savings in a risky venture ultimately led to financial ruin.
• I can't believe you made such a foolheaded mistake by leaving your keys in the car.
• Stop being so foolheaded and listen to reason for once.
• Her foolheaded determination to prove everyone wrong drove her to achieve great success.

adjective not properly prepared or thought out; impulsive or rash

adverb in a hasty or impulsive manner

• The soldier was reprimanded for going into battle with his weapon half cocked.
• Don't go into that meeting half cocked, make sure you're fully prepared.
• He always shows up to parties half cocked, never fully sober.
• She went into the job interview half cocked, not fully understanding the position's requirements.