The most obvious one I have experience with is guys refusing to wear a helmet while riding a motorcycle because they're so tuff and manly and they "just won't crash".
I wear a helmet because it will protect my beautiful face if I fall off, and because it keeps bugs and birds from hitting the aforementioned rugged bearded handsomeness at high speeds thus preventing some accidents, and because I can have one with a cool design on it.
That's because they were threatening anyone who made fun of ck being shot.