A: Don't ride your bike unless you're wearing a helmet!
B: I don't like helmets. They mess up my hair!
A: It's better to mess up your hair than to mess up your head!
B: I won't fall. I'm a good bike rider.
A: Accidents happen very easily.
B: I've never fallen before!
A: There's a first time for everything.
B: I'll be very careful.
A: If it wasn't so dangerous, there wouldn't be a helmet law.
B: What is the helmetlaw?
A: Children have to wear helmets until they're eighteen.
B: I suppose wearing a helmet won't be too bad, then.